For much of the electorate, Europe is now the issue that determines party allegiance. This cleavage has overwhelmed voters’ views on almost everything else

Are voters motivated by policy preferences or partisan identities? Bryan Schonfeld and Sam Winter-Levy argue that the British Conservative Party’s sudden change in Brexit policy (following the surprising result of the 2016 referendum) offers a unique opportunity to study partisanship in the context of a natural experiment. They find evidence that voters care primarily about policy: pro-EU Conservatives disaffiliated from the party, while Eurosceptics became more likely to identify with the Conservatives. These findings suggest that voters are sufficiently policy motivated to change parties if they disagree with their party on important issues.