Districts, Party Discipline and Polarization

Joint with: Michael Castanheira - ECARES, Free University of Brussels

We analyze single member district, plurality rule legislative elections between national parties and local candidates. Parties are informational intermediaries. Candidate selection by national parties can be centralized or decentralized. We show that a national party would support (respectively, oppose) laws that marginally increase intra-party discipline if and only if party discipline is initially high (respectively, low). We also prove that, under decentralized candidate selection, parties always support a decrease in party discipline and promote selection procedures that are not too partisan. These two sets of results imply that the political regimes that start from different institutional environments should move further apart in time. We provide some evidence on the US and the UK that supports this prediction. Our results also prove that, if they can choose, parties prefer decentralized candidate selection procedures if intra-party discipline is weak and centralized procedures if intra-party cohesion is strong. Finally, our results allow us to provide a novel rationale for why Duverger’s law seems to apply in the US but not in other democracies such as the UK or India.

For more information, contact Antonio Merlo.