Brexit spillovers: how British domestic politics affected support for European integration in remaining member states

A large body of research investigates the diffusion of policies and political developments across countries, and analyzes its consequences for mass preference formation and electoral accountability. While we know that voters look at policy outcomes abroad to assess domestic performance, the politics through which policies emerge can also be informative to voters. To understand whether voters learn from observing other countries’ domestic political struggles, we analyze the international reverberations of British Brexit politics. We argue that, although it may be too soon to assess the actual consequences of Brexit for the UK, political struggles during the negotiations may have provided information about the political feasibility and desirability of leaving the EU. We analyze three key events in recent British politics that happened during the fieldwork of two surveys, and a natural experiment that leverages random variation in exposure to Brexit-related information. Results confirm both a deterrence and an encouragement effect of Brexit on support for leaving the EU in remaining member states, and provide causal evidence of the benchmarking mechanism. These findings show how news coverage of other countries’ domestic politics can simplify voters’ decision-making by reducing the uncertainty associated with alternative policy choices. They have implications for theories of EU support and for the prospects of the current backlash against political globalization