This paper investigates the ideational leadership of EU institutions. It conceptualises ideational leadership as the capacity of institutional actors to steer EU policymaking through ideas about principles, programmes and instruments. Such ideas operate at three levels of generality – at a macro level, philosophical ideas concern the values and principles of the EU; at a meso-level, programmatic ideas pertain to agenda-setting and strategic objectives; and at a micro-level, policy ideas reflect specific policy instruments. Based on these ideational levels, the paper puts forward three distinct types of ideational leadership, i.e. normative leadership, which defines the values and principles of the EU; political leadership, which articulates EU priorities and action programmes; and technical leadership, which influences the elaboration and establishment of EU policy tools. To assess the validity of the proposed theoretical approach, the paper examines two case studies of EU foreign policy: the 2014 Russia’s annexation of Crimea and its subsequent destabilisation of Eastern Ukraine; and the 2022 Russia’s full-scale invasion of Ukraine and ensuing war. It analyses 1600 speeches for a total of over 100k sentences using text-as-data approaches. It finds that programmatic ideas are the most prevalent, while policy ones are relatively sparser. However, their relative prevalence varies across actors and over the two periods. The paper contributes to the literatures on ideational leadership, EU foreign policy institutional dynamics and the integration of member states’ core state powers.