Incumbent Democrat Jim Costa’s reelection bid anchors trader consensus in California’s 21st congressional district, a Central Valley seat that shifted modestly leftward after redistricting and now leans Democratic by roughly six points based on recent presidential voting. Cook Political Report, Inside Elections, and Sabato’s Crystal Ball all rate the race Likely Democratic ahead of the June 2 top-two primary, reflecting Costa’s long tenure, moderate positioning, and established fundraising edge. With no major Republican challengers emerging to close the gap and voter registration favoring Democrats, the implied probability of a Democratic hold remains elevated, though the November general election outcome could still shift if turnout patterns or late primary results alter the top-two matchup.