Replication Data for: When does accommodation fail? The electoral consequences of intra-party divisions and mainstream party strategies

Dominant spatial theories suggest that mainstream parties can contest the success of niche parties by accommodating their positions. However, research shows that this strategy often results in electoral punishment for mainstream parties. The article proposes intra-party divisions as a novel explanation of accommodation failure. Divided parties are unable to credibly and competently commit to accommodative shifts, alienating niche party voters. They also fail to persuade voters sceptical of accommodation. These propositions are empirically tested on the key niche issue of European integration. Examining election outcomes and dyadic vote switching in 14 Western European countries between 1988 and 2025, the article finds that divisions spoil any electoral benefits of shifting Eurosceptic. Additional analyses highlight an underlying valence logic, where divided accommodators lose voters to non-Eurosceptic rivals. Hopes of winning back Eurosceptic voters through accommodation appear futile, as the strategy shows little effect on voter flows between mainstream and Eurosceptic parties.