In recent years, an increasing number of political parties in developing countries have democratized their candidate selection processes. Although primary elections are expected to limit party elites’ ability to decide who gets to run under the party’s ticket, the question of party elite influence in primary elections has received little empirical attention. This paper advances an argument linking primary outcomes to the strategic behavior of subnational party elites, particularly those who control key resources to mobilize the primary electorate in favor of their preferred aspirants. I provide support for this argument using data on legislative candidate selection in Mexico. The results indicate that a party’s legislative primaries (1) have greater turnout and (2) are decided by considerably larger margins in states where that party controls the governorship. Importantly, I show these patterns are driven by governors who have more time left in office, and thus have greater incentive to invest resources in primary races. These results have important implications for the study of legislative politics in Mexico. While it is widely assumed that governors’ influence the behavior of national legislators through their control over ballot access, this paper presents empirical evidence showing that governors indeed shape their parties’ nomination processes and identifies some of the channels by which they do so.