How do organized interests shape the agenda of science, technology, and innovation (STI) policy in the European Union? I address this question by investigating how a proposal for costly AI research infrastructure made it onto the agenda of high-ranking EU policymakers. Drawing on the political science literature on interest groups and agenda-setting, I argue that three transnational scientific associations drew attention to the proposal through direct and indirect lobbying. I rely on process tracing, semi-structured expert interviews and participant observation to outline the tactics that the associations used to get their preferred policy proposal onto the EU policy agenda. In doing so, I show that the scientific associations in question succeeded in putting their proposal for costly AI research infrastructure on the EU agenda because they used their expertise and reputation to gain access to key policy fora, tapped into existing innovation policy discourses at the EU-level and appealed to values that are central to the EU’s identity and purpose. My findings add to the study of STI policymaking in the EU, which has so far almost exclusively focused on the role of individual high-level policymakers or political institutions in STI agenda-setting while neglecting to study that of organized scientific interests.