Party Cues and Support for International Cooperation: Experimental Evidence on Fiscal Integration Preferences

International cooperation is increasingly contested. While governments' efforts to deepen international integration in the past were buoyed by citizens' tacit support, the politics of international cooperation is increasingly scrutinized in the domestic arena. Driving the globalization backlash, political challengers parties have successfully politicized international cooperation across the world – leading governments to increasingly pay attention to their constituents' preferences when negotiating at the international level. This suggests that governments and mainstream parties are at the behest of political entrepreneurs and a critical public. Yet, a broad literature on cueing effects suggests that political actors have considerable leeway to shape public preferences – also about international cooperation. Using a pre-registered information treatment experiment in five countries, we examine the effect of in- and out-party cues about fiscal integration in the European Union (EU). The experiment was fielded at a moment in which questions pertaining to fiscal integration were highly salient (July 2020). We find that political parties have ample latitude to shape citizen preferences about far-reaching international cooperation, as both in-parties and out-parties significantly affect citizen preferences about fiscal integration. This pattern is remarkably robust across countries and across citizens with different levels of ideological commitment to the EU. We further find that both successful and unsuccessful in-party cues significantly affects citizens' certainty about their preference for international cooperation – suggesting the importance of elite communication beyond direct persuasion.