Party Control of Party Primaries: Party Influence in Nominations for the US Senate

Scholarship on primary election outcomes has largely ignored the ability of political parties to shape outcomes and influence the decisions of candidates to compete for the party's nomination. Only recently have theories of parties as networks of policy demanders suggested that parties influence the candidate nomination process. Previous attempts to document party control of primaries, however, have only tested these theories on small or unrepresentative samples of primary races or have looked at general election results after the party's nominee has already been selected. Using a simple and easily understood measure of party support, I show that candidates who are less connected to the party are less likely to win and also less likely to remain a candidate in the primary. I find that parties not only are effective in helping candidates win but also are influential in excluding certain electoral options from being presented to primary voters.