There is little doubt that institutional leadership matters in EU politics. However, political scientists still face the problem of conceptualizing and assessing the impact of leadership: How can we know that a given policy outcome or institutional change is caused by the leadership of a particular institution or state? In this paper, I argue that comparisons or counterfactuals cannot solve this problem in a satisfactory manner. In addition, we need to study the causal mechanisms by which leadership affects outcomes. The appropriate method for doing so is process-tracing. Starting from the proposition that a leader wields influence by translating power resources into strategies, I suggest a way to conceptualize and trace these leadership strategies. Furthermore, I illustrate the added value of this approach by applying it to two cases of EU policy-making: First, I analyse the leadership strategies employed by the European Central Bank when in 2012 it contained the eurozone crisis by announcing the so-called Outright Monetary Transactions. Second, I examine the role of Germany in shaping a common EU response to Russia’s annexation of Crimea in 2014. While in both cases it has been argued that institutional leadership made a crucial difference with regard to the outcomes, the causal mechanisms proving the leaders’ impact have not been studied so far. Hence, this paper suggests a fruitful way of studying institutional leadership in the EU, and it sheds light on the strategies used by the ECB and Germany in combatting the EU’s various crises.
