Despite the growing body of qualitative evidence suggesting collusion between gangs and political parties in various parts of the world, little has been done to study quantitatively the extent to which criminal organization may affect political elections in such context. Using police data and voting results in El Salvador, we find that homicides in gang-controlled neighborhoods tend to decrease by 24 percent of the mean during electoral seasons. We also estimate that gang control is associated with a 2.75 percentage point increase in electoral participation. These effects are especially significant in the neighborhoods where political parties have a strong voting base. Consistent with the interviews we conducted, this suggests that parties negotiate with gangs to mobilize electoral participation in the areas where they are more likely to receive electoral support and thus increase their chances of winning.