Incumbent Democrat Mike Thompson holds a commanding position in California's 4th congressional district top-two primary scheduled for June 2, 2026, reflecting his long tenure representing the Napa and Gold Country area and consistent fundraising edge. Democratic challenger Eric Jones, a businessman and nonprofit executive endorsed by figures such as Bernie Sanders, has emerged as the main intra-party competitor, drawing attention in local media and donor circles. Several Republicans, including nurses and business owners, also appear on the ballot but face the district's strong Democratic lean. The race remains low-drama heading into election day, with no major late developments altering the established candidate field or procedural timeline.