Incumbent Mike Thompson, a longtime Democratic representative, faces a primary challenge from Eric Jones in California's 4th Congressional District, a solidly Democratic seat. The June 2, 2026, top-two primary determines which two candidates advance to the November general election. Jones has drawn attention through strong fundraising relative to other challengers, while multiple Republican candidates including Sharon Brown split the opposition vote. No other major developments have shifted the race in recent weeks, leaving candidate resources, endorsements, and voter turnout in the district's Democratic-leaning areas as the primary factors ahead of the primary.