Abstract
Background: Political polarization can influence policy responses, particularly during crises. While institutions aim to counterbalance these effects, their capacity to do so under stress remains underexplored. This study examines whether mayoral partisan ideology affected pandemic policymaking in Brazilian municipalities, a highly polarized context with a severe COVID-19 health burden. Methods: We used a regression discontinuity design in 599 closely contested mayoral elections in 2016 to identify causal effects of partisan ideology on municipal pandemic responses in 2020. The analysis focused on formal policy measures and behavioral outcomes, particularly compliance with social isolation. Results: Mayoral partisan ideology had minimal influence on formal pandemic policymaking at the municipal level, challenging assumptions based on national partisan cues. However, municipalities led by right-wing mayors showed lower compliance with social isolation in the short term, despite no significant differences in formal policies and overall compliance across the first year of the pandemic. Conclusions: These findings highlight the complexity of partisan influence on health policymaking during crises. While national politics may shape public discourse, institutional structures and political and electoral interests can mitigate ideological effects on local policymaking.