**Incumbent Democrat Lateefah Simon advanced from the June 2, 2026 top-two primary alongside fellow Democrat Jamie Joyce, while the lone Republican entrant received negligible support as a write-in.** California's 12th district, encompassing much of San Francisco, maintains strong Democratic voter registration advantages and a consistent history of large margins for Democratic candidates in federal races. With no Republican on the November 3 general-election ballot, the outcome is structurally limited to a Democratic victor. Traders price this near-certainty into the 95.5% Democratic consensus, reflecting the district's partisan baseline and the absence of any competitive cross-party challenge. The slim Republican share accounts for residual uncertainty around turnout anomalies or unforeseen disqualifications, though such shifts lack precedent in this seat.