Most research on the electoral penalty of candidate ideology relies on betweendistrict or longitudinal comparisons, which are confounded by turnout and ballot composition effects. We employ a within-precinct design using granular precinct-level election data from the MIT Election Data and Science Lab (2016-2022) alongside comprehensive data on candidate ideology. By analyzing within-precinct variation in two-party vote shares for contests simultaneously appearing on the same ballot, we isolate the effect of ideology on vote choice among a fixed electorate. We estimate how voters respond to candidate ideology in terms of vote choice across diverse electoral contexts, holding turnout fixed. A standard deviation change in the midpoint between candidates results in an average vote share penalty of 0.6 percentage points. The effect varies with office type, information availability, incumbency status, and partisan geography. Overall, we find that gains associated with ideological moderation are relatively modest and likely secondary to turnout effects.