Six of the nine Missouri state senators running for re-election—all Republicans—face contested primaries. That equals 67% of incumbents seeking re-election, the highest rate since 2014. This is also the first cycle since 2014 with more than one Republican incumbent facing primary challengers.

A primary is contested when there are more candidates running than available nominations, meaning at least one candidate must lose. Historically, however, Missouri incumbents tend to win contested primaries.

Since 2014, only one state senator—Sen. Jacob Hummel (D)—has lost to a primary challenger in Missouri. This means that during that time, 86% of incumbents in contested primaries ultimately advanced to the general election.

The total number of contested primaries—including those without incumbents—is also at its highest point this year. With 17 districts holding elections, there are 34 possible primaries every election cycle.

This year, there are 13 contested primaries, all among Republicans. This is the first time since 2014 without any contested Democratic primaries in the chamber. All but four districts up for election will have a contested Republican primary.

The filing deadline for candidates running for state Senate in Missouri was March 29. Candidates filed to run for 17 of the state’s 34 Senate districts.

Overall, 51 major party candidates filed to run in the chamber this year: 12 Democrats and 39 Republicans.

Missouri has been a Republican trifecta since the party won the governorship in 2016. Republicans currently hold a 24-10 majority in the Senate and a 108-48 majority in the House.

Missouri’s primaries are scheduled for August 2, the tenth statewide primary date of the 2022 state legislative election cycle.