Party Realignment and Single-Issue Voters:  Evidence from Brexit

Abstract

This paper studies the effects of the referendum on the British exit from the European Union on the Conservative Party in the United Kingdom. We look at the change in positions of Conservative Members of Parliament using a novel dataset of their opinions on British membership of the EU between 2015 and 2022. We explore the role of the United Kingdom Independence Party's collapse in these trends and contrast the outcomes with the 1975 referendum, focusing on the possible roles of discipline and entryism. Our finding that Conservative MPs who resisted switching to a pro-Leave position paid a significant electoral cost underscores that weakening political parties can render them vulnerable to hostile takeovers.

Keywords: Referendums, single-issue politics, political parties