Incumbent Democrat Mike Thompson and challenger Eric Jones, both Democrats, advanced from the June 2026 top-two primary to face each other in the November general election for California's 4th congressional district. Forecasters rate the race Safe or Solid Democratic, reflecting the district's voter registration edge for Democrats and its partisan lean even after 2025 redistricting under Proposition 50. With no Republican advancing, trader consensus assigns overwhelming probability to a Democratic winner. A Republican victory would require an unprecedented reversal in a district where Democratic candidates have dominated recent cycles. Late developments such as major scandals or health events involving both nominees remain the only realistic paths to altering the outcome before November 3.