Incumbent Representative Mike Thompson seeks renomination in California's 4th congressional district primary on June 2, facing Democratic challenger Eric Jones alongside a crowded Republican field that includes Sharon Brown, Mandy Ghusar, and Jimih Jones. The nonpartisan top-two format advances the two highest vote-getters to the November general, where the district's strong Democratic tilt and Thompson's 28-year incumbency create structural advantages. Candidate filing closed in March with no late entries or major endorsements reported since, leaving fundraising records and voter turnout in the Napa Valley and North Bay counties as key variables. Historical patterns of low primary turnout and fragmented opposition support consolidation around the sitting member ahead of the general election.