What happens when open-list proportional representation elections replace closed-list ones? This article reveals that parties with internal disagreement on key issues may benefit. Under a closed system, voters tend to support unified parties; however, with open lists allowing candidate selection by voters, specific candidates within divided parties can attract supporters.

This effect was demonstrated using experimental data from a hypothetical European Parliament election in the UK. The study found that when switching to an open-list ballot format, support shifted away from UKIP (the Eurosceptic party) and toward individual Eurosceptic Conservative Party candidates.

Experimental Findings:

The shift occurred because voters previously loyal to UKIP were drawn to alternative Conservative candidates they might not have otherwise considered.

Key Implications:

This suggests that open-list ballots can restrict support for single-issue parties while potentially allowing more moderate or multi-issue parties greater influence. The results highlight the complex relationship between electoral systems and party behavior.