The contested nature of political leadership in the European Union: conceptual and methodological cross-fertilisation

European leaders have struggled to find common responses to the polycrisis the EU is facing. This crisis of leadership makes it urgent that scholars provide a better understanding of the role and impact of leadership in EU politics and policy making. This article prepares the ground for a collection of contributions that addresses this need by strengthening old and building new bridges between the academic domains of European studies and leadership studies. It opens with a discussion of the contested concept of leadership in the context of the European polity and politics, challenging the conventional view that leadership is necessarily a matter of hierarchy. Moreover, it argues that rather than leaderless, the EU is an intensely ‘ leaderful ’ polity. Subsequently, this introduction identifies four key debates in contemporary EU leadership research and discusses the value and insights the contributions in this special issue bring to these debates.

policy making. In response to this need, this special issue aims to strengthen old and build new bridges between the academic domains of European studies and leadership studies by fostering conceptual and methodological cross-fertilisation.
In this introduction, we argue that one of the most salient lessons EU scholars can draw from leadership studies is to acknowledge the complex nature of the process of leadership. Instead of conceptualising leadership as centralised power wielding by a stand-alone leader, it is best understood as a collective and reciprocal interaction among (multiple) leaders and their followers. This is especially the case in the context of the European Union, where leadership is exerted by several autonomous though interdependent actors who pool their powers to lead the European Union together (T€ ommel 2014). Understanding leadership as a collective and reciprocal endeavour therefore brings EU leadership studies closer to the true nature of their research object (M€ uller 2019).
The many enlargements of the EU have substantially altered the set-up of interests and increased the diversity of actors in the EU's policy-making process. This makes reliance on leadership by one (or a tandem of) member state(s) unlikely and severely limits the room for pan-European agreement (Krotz and Schild 2013;Paterson 2011;Schild 2010). In addition, recent years have seen a trend towards the polarisation of European politics: The Eurozone crisis, the European refugee crisis and the rule of law crisis have shown that the EU has significant consequences for its member states and people, but still does not constitute a cohesive political community with common norms, values and policy priorities (Majone 2014;Scharpf 2011). In fact, these crises may have fostered an increasing divergence of interests among the member states and the rise of the so-called 'constraining dissensus' (Hooghe and Marks 2009). In such an environment, even the heroes of Europe's past would be hard pressed to offer a solution to the EU's crises.
This article introduces a collection of contributions devoted to the study of the complex nature of political leadership in the European Union. It proceeds as follows: First, we discuss the concept of leadership and its contested usage in the context of the European polity and politics. Following the state of the art in leadership studies and reflecting on the contributions to this volume, the article challenges the conventional view of leadership as a matter of hierarchy and domination. We argue, further, that the fragmented, multi-level system of the European Union does not make it an 'anti-leadership environment' (Helms 2017: 2;cf. Hayward 2008). Rather, the EU is an intensely 'leaderful' polity (Raelin 2005;cf. Sergi et al. 2016), and thus a very interestingeven the ultimatedomain for the study of leadership (cf. M€ uller 2019).
Second, we provide an overview of past and present trends in the study of leadership in the European Union. We identify four themes that are central to the scholarship and that have guided our collection of articles: leadership as (German) hegemony; leadership as impact; leadership as soft power; and leadership in context. Providing an overview of the central debates in contemporary (EU) leadership research, we discuss the value and insights the contributions in this special issue bring to these debates. Finally, we summarise the main findings of the articles herein. By exploring insights and methods from both European and leadership studies, this special issue aims to provide a more comprehensive understanding of the complex nature of leadership in the European Union.

A leaderful Europe
In recent years, the inability of European political leaders to tackle the EU's 'polycrisis' has led observers to argue that the EU lacks sufficient and strong leadership (Cramme 2011;Hayward 2008;McNamara 2010;Westfall 2013). Such diagnoses almost invariably result in calls for robust, visionary leadership directed at certain powerful national leaders (most notably German chancellor Angela Merkel), the French-German tandem or the president of the European Commission (Hayward 2008: 3). In addition, they are routinely accompanied by reminiscences about the days when European leaders did have the resolve, personality and belief to provide 'true' leadership.
There is a certain logic to such a call for strong leaders: When decision making stagnates, a combination of agency, vision and power may be the only force left to turn to. However, the proposition that the EU's polycrisis may be solved by political leadership in the form of a visionary 'lone ranger' is myth-based at best ( Van Esch 2017). First of all, the European Union 'lacks a clear leadership structure' but rather resembles a fragmented polity with a complex system of multi-level governance (T€ ommel and Verdun 2017: 1;cf. Cramme 2011;Hayward 2008;Helms 2017). As such, it is no surprise that a 'lone-ranger' conception of EU leadershipif it is a form of leadership at allis doomed to fail.
However, and more importantly, calls for strong leadership are also misleading from the perspective of the state of the art of leadership research. In contemporary leadership studies, leadership is seen as involving the opposite of lone rangers and domination (Brown 2014). Although there is no single agreed-upon definition in the literature, three central characteristics are generally held as being constitutive of leadership: First, leadership is a reciprocal process involving both the leader(s) and a set of followers (Elgie 2015;Nye 2008); second, leadership is about attaining goals that are mutually desired by both the leader(s) and the followers (Burns 2010(Burns [1978; Haslam et al. 2011); and third, such goals are attained through influence and persuasion rather than coercion (Blondel 1987;Burns 2010Burns [1978; Cronin and Genovese 2012).
Of course, power and authority may play important roles in the exercise of political leadership, but they should not be confused with it (M€ uller 2019). Whereas power and authority imply a unidirectional hierarchy of political decision making, political leadership derives from the reciprocal process between leaders and followers, in which individual leaders exert influence rather than coercion (Kellerman 1984). As illustrated in the contribution of T€ ommel in this special issue, holding an office may grant authority and resources, but an institutionally weak office does not a priori preclude the exercise of leadership by its incumbents (T€ ommel 2019; cf. M€ uller 2016, 2017, 2019).
The missing ingredient for transforming power and authority into leadership is the potential follower and the bond between the leader and the follower ( Van Esch 2017). While leadership may be exerted by individuals, institutions or collectives, their followers may range from the inner circle of a leader via those people who actively participate in the decision-making process to the citizens in their constituency (Kellerman 1984). Moreover, the bond between the leaders and their followers may vary. It may be merely transactional in nature, implying an exchange of valued (material or non-material) commodities. However, the relationship may also be transformational, with 'leaders and followers rais[ing] one another to higher levels of motivation and morality' (Burns 2010(Burns [1978: 83), or rooted in a shared ideological vision or social identification (Haslam et al. 2011;cf. Van Esch 2017).
In any case, in contrast to domination or coercion, leadership presumes followers have a choice to follow or not, and as such leaders have to relate to followers' preferences, devotions and values (Burns 2010(Burns [1978). Neither the leader per se nor the exertion of naked power should be confused with leadership; they are only parts of the equation (M€ uller 2019), and the image of a hero-leader is more a myth than reality whether in the national or the European arena (Brown 2014).
Just as it is oblivious to the more nuanced concept of leadership developed in the domain of leadership studies, the diagnosis that the EU needs strong and visionary leadership to tackle its polycrisis is also potentially toxic in light of the EU's perpetual legitimacy crisis. The literature on the legitimacy of the European Union rarely invokes the concept of leadership and speaks predominantly in terms of institutional democratic deficits or identification (Follesdal and Hix 2006;Majone 2014). Nonetheless, from a leadership perspective this literature suggests that, rather than lacking strong leadership, the EU suffers from a broken or soured bond between leaders and followers ( Van Esch 2017). This diagnosis also increasingly applies to the relationships between EU leaders. In the enlarged and politicised EU of 28 (after Brexit, 27) member states, relations among the main decision-making institutions and the member states seem to be increasingly strained and attempts to engage in (co-)leadership are highly contested (M€ uller and Van Esch 2019; Schild 2019; Schoeller 2019; T€ ommel 2019). The lack of legitimate EU leadership thus also affects the internal workings and effectiveness of the European Union.
The advantages of strong and centralised EU leadership are clear: It promises determined and effective action in a system of pluralistic, nonhierarchical institutions that lacks a clear structure of government and opposition. However, such a hierarchical perspective on leadership is very likely to exacerbate the EU's legitimacy problems for it is at odds with both the democratic ideals of the European Union and the sovereignty of its member states (Barber 1998;Kane and Patapan 2012). Calls for Germany in particular to take the helm are also problematic from a historical perspective ( Van Esch 2017). In times of crisis or moments of deadlock, it is tempting to invoke power and determination. However, unilateral and hierarchical wielding of power does not constitute leadership and it is also likely to be toxic in a historically burdened Europe struggling to increase its political legitimacy.
All in all, the diagnosis of the EU leadership crisis as signalling a lack of strong leadership seems to have been driven by a misunderstanding of what actually constitutes leadership. Challenging the conventional view of leadership as based in hierarchy and domination, this introduction argues that the European Union is not an anti-leadership environment (Helms 2017: 2;cf. Hayward 2008: 2). To the contrary, the EU is an intensely 'leaderful' polity (Raelin 2005;cf. Sergi et al. 2016) and purposely designed as such (Hayward 2008;Helms 2017). Moreover, although the scholarship on EU leadership and on legitimacy have developed separately, in reality the two phenomena are related. Calls for strong, centralised EU leadership may exacerbate the EU's legitimacy crisis, thereby reducing the effectiveness of its decision making.
Considering leadership as a collective endeavour and reciprocal process between leaders and followersas is the state of the art in leadership studieswe argue that the European Union is the ultimate domain for the exercise and study of leadership (cf. M€ uller 2019). The EU is a political system that combines a low level of political hierarchy with a high level of political, economic and social interdependence among the member states and EU institutions. This combination often makes the provision and exercise of leadership the best and sometimes only possible path to avoiding political deadlock. In other words, rather than being alien to the European Union, leadership has always been at the core of its political system.

The study of EU leadership: past and present trends
The contestation between the nature of EU political leadership and its scholarship is reflected in developments within the academic domain. Whereas during the early, enthusiastic phase of European integration in the late 1950s and early 1960s, scholars drew attention to European institutions and their protagonists' capacities to provide leadership (Cox 1969;Haas 2004Haas [1958), the aftermath of the Empty Chair crisis and the era of 'eurosclerosis' during the 1970s led to a relative decline in academic interest in leadership (cf. Haeussler 2015;Story 1980;Van Esch 2009). It was only with the activism of the Delors presidency in the late 1980s that such interest revived. Even then, the study of leadership in the EU remained a largely empirical exercise. Due to the prevailing institutional nature of European studies, leadership never became an integral part of any of the theories of European integration (Beach and Mazzucelli 2007;M€ uller 2019).
Recent publications on EU leadership are more theoretical as well as more diverse in terms of their research questions and focus. The field has also increasingly started to integrate theoretical and methodological insights from the domain of leadership studies and other relevant disciplines. Four themes can be identified as central to this more contemporary literature on EU leadership: (1) leadership as (German) hegemony; (2) leadership as impact; (3) leadership as soft power; and finally, (4) leadership in context. These four themes represent the major theoretical debates in contemporary EU leadership research (Grint et al. 2016;Helms 2017;Rhodes and 't Hart 2014;'t Hart 2014;T€ ommel and Verdun 2017). While providing an overview of these central debates, this section also discusses the value and insights the contributions in this special issue bring to these discussions.

Leadership as hegemony
Examining EU leadership from the perspective of hegemony is a longstanding theme in European studies. With the fall of the Berlin Wall in 1989 and the resulting reshuffle of the balance of power in the EU, students of EU leadership became interested in Germany's new role as a, or even 'the', leading power in Europe (Bulmer and Paterson 1996;Kaelberer 1997). Other scholars have taken a slightly broader focus and asked to what extent the French-German tandem is (still) able to steer EU policy (Krotz and Schild 2013;Schild 2010;Schoeller 2018). In light of Germany's performance in the Eurozone and refugee crises, the question of Germany's hegemonic role re-emerged, further stimulating this field of research (Bulmer and Paterson 2013;Otero-Iglesias 2017;Paterson 2011;Schoeller 2016). Studies in this subfield have rarely explicitly used leadership theory, relying mainly on hegemonic stability theory. Nonetheless, it is clear that this branch of literature makes a valuable contribution to the debate on the nature of EU leadership. The concept of hegemony derives from international relations theory and presupposes the absence of a formal hierarchy. Thus, while it does not feature in the more nationally and sub-nationally oriented leadership studies, it is applicable to (certain domains of) the EU polity.
While in their traditional forms, theories of hegemony focus on hard power and dominance, later additions further a conceptualisation of leadership that is more in correspondence with the current state of the art in leadership studies in three ways. First, as hegemony 'rests on the subjective awareness by elites in secondary states that they are benefitting' (Keohane 1984: 45), the concept brings home the inseparable link between legitimate and effective leadership: Followers must accept the hegemon as their rightful leader for it to achieve its goals. Moreover, hegemony also presumes a willingness on the part of the hegemon 'to sacrifice tangible short-term benefits for intangible long-term gains' (Keohane 1984: 45).
The contribution to this special issue by Schild is squarely placed in this contemporary perspective on hegemony. The article adds to the debate by drawing an explicit comparison between different conceptions of leadership and hegemony and teasing out the differences between them (Schild 2019). Moreover, by combining insights from hegemonic stability literature and leadership studies, the article develops a more structured, precise and generalisable operationalisation of hegemony than previously available in the literature. Schild applies this framework to assess Germany's leadership role in the Eurozone crisis and concludes that Germany was unable to play the part of a hegemon as it lacked the resources to decisively shape the economic constitution of the euro area along the lines of its core preferences.
Second, most contemporary interpretations of hegemonic stability theory explicitly acknowledge the significance of soft power sources and the power of ideas (Keohane 1984;Schild 2019;see below). This is especially the case for the way critical theory has interpreted the concept of hegemony and the scholars that have focussed on the workings and power of ideological hegemony. In this perspective, hegemony is seen as a political system that is deeply rooted in the (power) relations within society (Cox 1993: 51). It is thus not imposed on society by political leaders but emerges from the underlying social fabric (Bulmer and Joseph 2016). Leaders may reify the hegemonic ideology and as long as hegemony remains strong and relatively uncontested, leadership that respects the limits of the hegemonic ideology may be successful. Only when hegemony is significantly challenged or falters do 'hard' power and strong leaders become necessary to uphold the system (Bates 1975). Due to its persuasive, or socialising nature, ideological hegemony in itself 'is enough to ensure conformity of behaviour in most people most of the time' (Cox 1993: 52).
From this perspective, the question of legitimacy takes on an entirely different meaning. Truly hegemonic ideologies are internalised by social actors and reified in social interaction, and as a result deemed legitimate by followers in the hegemonic system. At the same time, this raises serious moral questions regarding the state of awareness of the actors in such a system and the extent to which the followers' support suffices to make the exertion of leadership legitimate (Bates 1975: 352;Cox 1993). In any case, the critical perspective on hegemony illustrates how misleading it is to speak of ideas as 'soft' power. For who needs hard power, when ideological hegemony would already ensure conformity in most people?
Finally, building on the premises of the English School in international relations, Ian Clark argues that both consensual legitimacy and agency are a necessary part of hegemony. First, similarly to the definition of leadership forwarded in this introduction, he argues 'hegemony is a status bestowed by others, and rests on recognition by them' (Clark 2009: 24). This shifts the focus 'away from the attributes of the putative hegemon, and the resources at its command, towards the perceptions and responses of the followers' (Clark 2009: 27). In addition, rather than a mere product of the international power structure, in his view, hegemony also involves a policy choice on the part of the hegemonic state. As is shown in the contribution of Schoeller in this special issue concerning Germany and the European Central Bank: The possibility exists that a potential hegemon is actually unwilling to take on this role (Schoeller 2019; see also Clark 2009;Bulmer and Paterson 2013).

The nexus between leadership and impact
Closely associated with the topic of hegemony is the question of the nexus between leadership and its potential impacts. Given the complex and embedded nature of leadership, establishing a causal relation between leadership and its outcomes is difficult, especially in the fragmented and multi-level system of the European Union. As a result, scholars of EU leadership have focussed mainly on the capacities of the different European institutions, member states and key individuals to provide leadership and impact EU politics. Leadership studies of the European Commission, for instance, have tended to centre around its leadership and that of its presidents in specific policy areas and on the Commission's institutional capacity to influence European treaty negotiations (Beach 2005;Dinan 2016;Kreppel and Oztas 2017;T€ ommel 2013). Close attention has also been paid to the European Council, with scholars studying its leadership capacity, the potential impact of the rotating presidency and the effect of the balance of power among its members on European negotiation outcomes (Elgstr€ om 2003;Fabbrini and Puetter 2016;Tallberg 2003). Other European institutions whose leadership has been studied include the European Central Bank (Verdun 2017) and the European Parliament (Judge and Earnshaw 2008;Wilson et al. 2016). Finally, the effects of EU collaborative leadership have also been the object of study (Nielsen and Smeets 2018).
All these analyseslike scholarship into leadership in generalstruggle to a certain extent with establishing a credible link between leadership and its outcomes. In addressing this issue, Schoeller (2019) follows other scholars in dissecting the process of leadership into its various components. Different classifications of the components of leadership exist, but scholars largely agree that leadership involves: (1) having a purpose or leadership task; (2) (2019) explains, studies taking one of these first two perspectives often assume causal links between leaders' purposes or resources and final outcomes rather than actually empirically establishing them.
By contrast, scholars focussing on the 'process' of exerting leadership concentrate their research on the strategic behaviour of leaders and the interactions between different stakeholders and between leaders and followers. These scholars often use case-study research and interviews to provide in-depth accounts of these interactions to explain how leadership is translated into particular outcomes (T€ ommel 2019; Tallberg 2006).
Studies that define leadership in terms of its purpose, resources or process often use their particular conceptualisation of leadership to explain an outcome. This means that scholars applying these perspectives generally do not include the outcome of leadership in their definition of leadership but regard it as the dependent variable (partly) produced by the exercise of leadership. A notable example here is the work by Tallberg (2006), who uses process tracing and counterfactual analysis to develop an argument about the institutional resources of formal leaders and the effects these resources create concerning provision, process and outcome of formal leadership in multilateral negotiations. This is quite a different approach from studies using a 'result' perspective on leadership. Here, leadership is equated with successfully reaching a certain outcome. It is therefore of little value for those who seek to establish a causal relation between leadership and an outcome. Moreover, in studies that take a results perspective, often only a grand result like solving a crisis or inducing major policy reform is seen as true leadership. The vital tasks of preventing crises and conflict, protecting the collapse of the system or painstakingly maintaining the status quo against its daily challenges are seen not as leadership, but as 'mere' management (cf. 't Hart 2014: 8). The early scholarship in EU leadership was often based on a (implicit) leadership-as-result perspective. Leaders like Monnet, Delors and Kohl are among the usual subjects of study because they presided over defining projects in the process of furthering European integration, and the successful establishment thereof is ascribed to their actions.
Equating leadership with success (cf. Grint et al. 2016) is not an innocent semantic matter; it carries deep conceptual problems and consequences. For as the 'result' perspective renders the term 'successful leadership' tautological, it logically leads to the conclusion that no such thing as 'unsuccessful leadership' exists. As a result, relevant differences between concepts like 'unsuccessful leadership', 'non-leadership' and even 'bad leadership' are obscured (cf. Helms 2012). The moral connotation of equating leadership with success is also troublesome, especially so within EU studies because much of the scholarship in this field still adheres to the implicit assumption that progress towards further integration is inherently a good thing. This tendency is also apparent in the early scholarship on EU leadership, as suspiciously few studies are available of leaders who rejected the aim of ever closer unionlike De Gaulle and Thatcherdespite the fact that they have influenced the course of European integration as successfully as the celebrated heroes of European unification (Gilbert 2008).
Many contributions to this special issue conceptually and empirically distinguish between more or less successful leadership endeavours (M€ uller and Van Esch 2019; Schild 2019; Schoeller 2019; T€ ommel 2019). Schoeller (2019) in particular puts this question centre stage and uses theory-testing process tracing as a way to assess the causal relation between leadership and its consequences in a structured manner. He explicitly includes all the above-mentioned components of leadershipincluding the resultin one integrated analysis and offers credible claims about the extent to which one component fed into another, or not. He illustrates the value of his approach by applying it to the role of the European Central Bank (ECB) and Germany in the Eurozone and Ukraine crises, respectively. The analysis shows how important the context and leaders' followership are in shaping EU leadership and that despite their differences both the ECB and Germany acted as leaders 'by default'. At the same time, the contribution of T€ ommel rebuts Schoeller's argument that process tracing is the best way to make a credible claim of causality through its case study of the leadership by the European Commission president Jean-Claude Juncker (T€ ommel 2019).

Leadership as soft power
The third key debate in EU leadership research focuses on leadership as soft power. The EU has often been characterised as a soft or normative power, especially in its external leadership role (Manners 2006;Nielsen 2013). However, the EU can also be characterised as a soft power in terms of its internal leadership. For, although its treaties, regulations and the rulings of the European Court of Justice (ECJ) are binding and supersede national law, a complex array of factorsincluding the sovereignty of EU member states, the nature of their cooperation and level of interdependence, the consensus culture, issues of legitimacy and the historical context discourage the use of hard power in the EU's policy-making process (Nye 1990;T€ ommel 2014).
Scholarship on EU leadership has therefore shown a particular interest in the workings of soft power. This literature has long been dominated by single case studies, though comparative studies have gained traction in recent years (Dinan 2017;Endo 1999;Helms et al. 2018;Kassim 2017;M€ uller 2016Ross and Jenson 2017;T€ ommel 2017). Moreover, this literature has been strongly influenced by theories and methods from leadership studies.
Soft power leadership may be subdivided into three components: soft purpose, soft resources and soft process. Soft purpose is associated with interpretations of leadership missions that supersede the narrow and/or material self-interest of the leader. Literature on external relations suggests that this includes promoting certain values, ideologies or ways of life (Manners 2006;Nielsen 2013;Nye 1990).
In their contribution to this special issue, M€ uller and Van Esch contribute to this branch of the literature by providing a theoretical exploration of the conditions for exercising European collaborative leadership. Using the method of cognitive mapping, they provide an in-depth analysis of the beliefs of four teams of Commission presidents and German and French national leaders that oversaw major decisions in the field of European economic and monetary integration. Combining this analysis with an expert survey, they find that the more the beliefs of these leaders on European economic and monetary policy converge, the more successful they are in exerting collaborative leadership (M€ uller and Van Esch 2019).
Soft power resources refer to the use of non-material and informal resources like leaders' ideas, values, skills, personality traits and reputations ( (Brummer 2014;Van Esch and Swinkels 2015), whereas M€ uller applies a functional leadership approach (M€ uller 2019). Still others use computer-aided text analysis software to determine the tone of incumbents' speeches, while Van Esch uses cognitive mapping to determine the belief systems of political leaders (Olsson and Hammargård 2016;Tortola and Pansardi 2019;Van Esch 2014). Moreover, Tallberg (2003) shows that the presidency of the Council, which has often been considered as a 'responsabilit e sans pouvoir' (Devost 1984: 31), actually has a wide repertoire of 'soft' resources and may substantially shape the EU's policy agenda (Tallberg 2003).
Finally, from a process perspective, soft power involves the exertion of leadership by attracting, persuading and co-opting followers rather than relying on coercion or material incentives (Nye 1990(Nye , 2008. Within the field of European leadership, many studies adopt this perspective. Most of these consist of case studies offering in-depth analyses of political and policy-making processes leading up to historic European grand bargains or new regulatory regimes (Dinan 2017;Endo 1999;Kleine 2007;Ross and Jenson 2017;Verdun 2017). Some of these studies also theorise these soft power processes, for example, T€ ommel (2013) invokes Burns' distinction between transactional and transformational leadership in her comparative study of leadership by commission presidents.
Moreover, in the field of EU climate policy, Wurzel et al. (2017) adapt the framework of Young (1991) and conclude that entrepreneurial and cognitive EU leadership are prevalent and often work in conjunction. Using examples of the Copenhagen and Cancun conferences on climate change, Groen et al. (2012) show how the EU has to constantly realign ambition with political reality to direct and attain its goals in international negotiations.
Mixing a soft resource with soft process approach, the article by T€ ommel in this special issue uses a threefold analytical approachincorporating institutional structure, situational setting and personal qualitiesto compare Commission President Juncker's leadership performance across the different phases of his tenure. The article explains how, in a substantially constraining institutional and situational environment, Juncker still carved out considerable space for the exercise of political leadership. At the same time, T€ ommel emphasises that assertive and ambitious leadership performance alone does not guarantee leadership success at the EU level, which also requires a leader to show a capacity for adaptation and accommodation to cope with a variety of institutional and situational challenges, thereby exemplifying the importance of agency at the EU level (T€ ommel 2019).

Leadership in context
The fourth strand of EU leadership research focuses on the interaction between leadership and the situational context or domains in which it is exerted, as well as the question of how leadership is influenced by the broader environment of the European Union. In leadership studies, the context has been interpreted predominantly in an institutional sense (Elgie 1995;Helms 2005). However, some studies also focus on the influence of culture, zeitgeist or time ('t Hart 2014). In EU leadership studies, though institutions also feature as an important contextual factor, many studies also focus on how leadership and the specifics of a certain issuearea interact. Studies focussing on the cultural context and time are rare (but see Goetz 2017; Van Esch and De Jong 2019).
Nonetheless, overall the literature on EU leadership is very contextual and contains many rich case descriptions that illuminate how the specifics of the EU polity hamper or enable the exercise of leadership by various actors. The contextual take on leadership has been so dominant that different subfields may be distinguished within EU leadership studies focussing on specific policy areas. Among those most often studied from a leadership perspective are the EU's (external) environmental policy (B€ orzel 2000;Parker et al. 2017;Schmidt 2008), foreign policy (Aggestam and Johansson 2017; Amadio Vicer e 2016) and European economic and monetary policy ( Van Esch 2009, 2012. Reflecting the vast differences in institutional arrangements in this field and the thoroughly contextual nature of this work, scholars working within these subfields hardly speak to each others' studies. This special issue offers several contributions that transcend the boundaries of these subfields by comparing leadership across domains. Schoeller (2019) compares leadership efforts during the Eurozone and refugee crises, while the paper by T€ ommel (2019) takes a bird's-eye view of EU leadership in multiple issue-areas, for example, the negotiation of the Multiannual Financial Framework (2021-27). Moreover, the theoretical frameworks developed by M€ uller and Van Esch (2019), Schild (2019) and Swinkels (2019), though applied to leadership in specific issue-areas, are also applicable to EU leadership in general.
In addition, EU leadership has often been studied in specific situations or stages of the integration process. This branch of the literature includes studies of leadership during the 'big bangs' of European integration or negotiations over highly contested issues (Beach and Mazzucelli 2007;Kleine 2007;cf. T€ ommel and Verdun 2017). A lot of research focusses on leadership during times of crisis (Hodson 2013;Nielsen and Smeets 2017;Schoeller 2018;Van Esch 2014;Van Esch and Swinkels 2015). However, while research on the performance of EU actors in specific policy domains and situational settings has been widespread, such studies seldomly explicate the connection between leadership and context or make use of the insights and theories developed in leadership studies.
In contrast, the contribution by Swinkels to this special issue does exactly that. Building on the ideational turn in political science, Swinkels sets out to test the extent to which economic and political contextual factors like the level of Euroscepticism in a country, or economic fundamentals influence leaders' propensity to undergo belief change during the Eurozone crisis. Using the method of fuzzy-set Qualitative Comparative Analysis and a set of 12 national political leaders, she establishes that the combination of an increase in unemployment and unsustainable debt, a government ideology distinct from that of the other member states and an increase in Euroscepticism leads to changes in leaders' economic beliefs (Swinkels 2019).

Conclusion and outline of the special issue
This introduction prepares the ground for a collection of contributions that aims to foster a better understanding of the role and impact of leadership in EU politics and policy making. By strengthening old and building new bridges between the academic domains of European studies and leadership studies, each of the contributions provides new insights into salient debates, like that on the possibility of hegemonic EU leadership; the impact of EU leadership; soft power leadership; and EU leadership in context: The article by Schild (2019) critically assesses the idea of leadership as hegemony in order to better understand the leadership role of Germany and ideological hegemony, providing a more holistic understanding of the EU's polycrisis. In contrast to other observers, Schild concludes that Germany's hegemony was at best incomplete. The article by Schoeller (2019) addresses the impact of the (reluctant) leadership of Germany and the ECB and seeks to identify the mechanisms by which the actions of leaders link causally to the final outcomes. The contribution by M€ uller and Van Esch (2019) addresses the topic of soft power leadership by examining how leaders' motives and beliefs play a role in exercising collaborative European leadership. T€ ommel (2019) continues this debate by analysing how Commission president Juncker used soft resources and processes to exert influence on EU policy making and institutional change. Finally, the article by Swinkels (2019) explores the interaction between EU leadership and the broader political and economic context. She explains how distinct combinations of contextual factors may change the beliefs that inform decisions of Europe's leaders.
While addressing salient current debates on EU leadership and applying complementary approaches to its analysis, the contributions in this special issue challenge the view that leadership is a matter of hierarchy or domination. Advocating a more nuanced, soft, relational and contextual understanding of the concept of leadership, using the combined insights from European studies and leadership studies, the articles illustrate that the EU is an intensely 'leaderful' polity. As argued throughout this article, the European Union's low level of hierarchy and high level of interdependence have placed leadership at the heart of its political system from the very beginning.