Incumbent Mike Thompson’s 28-year tenure in California’s 4th Congressional District, combined with dominant fundraising and structural advantages in the state’s top-two primary system, anchors trader expectations ahead of the June 2 vote. A redrawn district and Democratic primary challenger Eric Jones, who has secured notable endorsements including from Senator Bernie Sanders, introduce the main source of uncertainty, though Jones trails significantly in campaign resources. Multiple Republican and independent candidates remain on the ballot but show limited financial viability. With the primary just weeks away, any late shifts in turnout among Democratic voters or unexpected Republican consolidation could influence which two candidates advance to the November general election.