California’s new congressional map, enacted via Proposition 50 in November 2025, serves as the primary driver of trader expectations for Democratic House seats in the 2026 midterms. The lines were drawn to convert three to five Republican-held districts into Democratic-leaning ones, building on the party’s current 43-9 advantage and targeting seats previously held by members such as Doug LaMalfa and Darrell Issa. June 2026 primaries largely confirmed the map’s effects, advancing Democratic candidates in most targeted districts while leaving only a handful of competitive races, including the Central Valley contest involving David Valadao. With few battlegrounds remaining under the revised boundaries and top-two primary rules, the implied probabilities heavily favor outcomes of 47 or 48 Democratic seats, consistent with the projected net gains from redistricting.