Twelve Congressional Incumbents Lose Primaries in 2026 Cycle

Twelve congressional incumbents lost their primaries during the 2026 election cycle, including two senators and ten House members. In the Senate, Donald Trump influenced the defeat of Republicans Bill Cassidy of Louisiana and John Cornyn of Texas by backing their challengers. Cassidy's loss followed his vote to convict Trump in a second impeachment trial, while Cornyn was defeated after Trump endorsed Texas Attorney General Ken Paxton.

In the House of Representatives, three Republicans—Dan Crenshaw, Thomas Massie, and Andy Ogles—lost their bids. Seven Democrats were ousted, frequently by challengers from the party's left flank or democratic socialists. These losses were driven by endorsements from Bernie Sanders and Zohran Mamdani, as well as redistricting efforts in Tennessee and Texas.

Notable defeats included long-serving members such as Representative John Larson of Connecticut and Representative Diana DeGette of Colorado. Some contests, including the race involving Thomas Massie, were reported as the most expensive House primaries in history.