Democratic House incumbents faced a record 272 contested primaries in 2026, far exceeding recent cycles and increasing exposure for sitting members. Multiple upsets occurred as progressive challengers defeated establishment figures, including Daniel Goldman and Adriano Espaillat in New York districts backed by local endorsements, Diana DeGette in Colorado, and others in Michigan, Connecticut, and Texas. These outcomes aligned with broader patterns of factional competition and outsider momentum within Democratic primaries. Trader consensus around 10-12 losses reflects the tally of verified defeats through late October alongside historical base rates for midterm primary attrition, while the narrow spread to 13-15 accounts for any remaining procedural or certification variables before full resolution.