Incumbent Mike Thompson and challenger Eric Jones, both Democrats, advanced from the June 2026 top-two primary in California's 4th district, creating a general election matchup with no Republican on the ballot. This outcome stems from the district's strong Democratic lean, reinforced by recent redistricting under Proposition 50, combined with Thompson's long tenure, fundraising edge, and establishment support that helped him secure the top primary spot. Forecasters rate the race Solid or Safe Democratic, aligning with trader consensus that a Democratic victory is all but assured by November 3. A Republican win would require an unprecedented reversal, such as a candidate withdrawal or disqualification, neither of which appears plausible based on current filings and campaign activity.