Do Municipal Voters Punish Partisan Candidates? Evidence from a Newly Partisan Municipal Election

While political parties structure competition in national elections, many municipal systems operate without party cues, often reflecting widespread public opposition to local partisanship. It is unclear, however, whether municipal voters would actually punish candidates for affiliating with political parties if given the opportunity. We study this question using Calgary’s 2025 municipal election — the first held after provincial legislation imposed formal parties on a historically nonpartisan system. Drawing on two large surveys fielded before and during the election, each embedding an identical conjoint experiment, we combine causal forest estimation of heterogeneous treatment effects with observational vote choice models to trace the party affiliation penalty from experimental estimates through to real electoral behavior. We find that voters impose a meaningful penalty on partisan candidates that grows rather than fades over time. This penalty is highly uneven: it is concentrated among citizens with strong anti-partisan attitudes and those who hold negative views of the provincial governing party that introduced the reform, suggesting that reactions to municipal parties reflect a mix of sincere anti-partisan commitments — the stronger channel — and conditional responses to the government responsible for the change. Experimentally estimated propensities to punish partisan candidates predict actual vote choice, confirming that anti-partisan sentiment shaped real electoral outcomes. These findings indicate that opposition to municipal parties reflects genuine normative commitments to independent local governance — commitments strong enough to resist accommodation under real electoral conditions — and help explain why nonpartisan equilibria prove so difficult to dislodge.