Ethnic group conflict is among the most serious threats facing young democracies. In this paper, we investigate whether the partisanship of incumbent politicians affects the incidence and severity of local ethnic violence. Using a novel application of the regression-discontinuity design, we show that as-if random victory by candidates representing India's Congress party in close state assembly elections between 1962 and 2000 reduced Hindu–Muslim rioting. The effects are large. Simulations reveal that had Congress lost all close elections in this period, India would have experienced 11 percent more riots. Additional analyses suggest that Congress candidates' dependence on local Muslim votes, as well as apprehensions about religious polarization of the electorate in the event of riots breaking out, are what drive the observed effect. Our findings shed new light on parties' connection to ethnic conflict, the relevance of partisanship in developing states, and the puzzle of democratic consolidation in ethnically divided societies.