Ken Calvert holds the leading position in the CA-40 race due to his stronger performance in the June 2026 top-two primary, where he captured roughly 35% of the vote compared to Young Kim’s 21%, allowing both Republican incumbents to advance to the November general election. Redistricting under Proposition 50 placed the two sitting members in the same district, with Calvert representing a larger share of the newly configured area that leans Republican based on recent presidential results. Ongoing negative advertising and competing endorsements have marked the intraparty contest, while Kim’s stronger second-quarter fundraising has narrowed but not closed the gap reflected in trader pricing. The outcome remains subject to turnout among remaining Democratic voters and late campaign dynamics through early November.