Incumbent Democrat Mike Thompson seeks his 15th term in California's 4th congressional district, facing primary challenger Eric Jones along with multiple Republican candidates in the June 2 top-two primary. Thompson's established name recognition, fundraising edge, and the district's strong Democratic tilt after redistricting anchor trader consensus on his advancement. Jones has mounted the most visible Democratic challenge through self-funding and issue-focused campaigning, positioning him as the likely second-place finisher. Republican entrants trail significantly in resources and visibility. The primary outcome will set the November general election matchup in a seat rated solidly Democratic by forecasters, with few recent developments altering the established positioning.