Rep. Mimi Walters, a Republican, has lost a bid for reelection in California's 45th Congressional District to Katie Porter, a Democrat.
With all precincts reporting, Porter has 52.1 percent of the vote, followed by Walters with 47.9 percent.
Walters has represented the district in the House since 2015.
Democrats have gained a majority in the House, with 235 seats in the next Congress. All of California's House seats have been decided; seven switched hands, all going to Democrats.
The number of votes cast for Democrats in House races has increased 55.0 percent from the 2014 midterms, compared with an increase of 25.6 percent for Republicans.
The district went for Democrat Hillary Clinton in 2016 by a margin of 5.4 points. Clinton won California by 30 points.
Data is from the Associated Press. This story may be updated if more information becomes available. It is powered by Heliograf, The Post's artificial intelligence system.