Democrats won in seven congressional districts previously represented by Republicans, all of which voted for Hillary Clinton in 2016. This reduced the California House Republican delegation by half and left the Republican Party with the fewest seats in California since just before the 1946 election cycle.
Republican incumbents Jeff Denham, David Valadao, Steve Knight, Mimi Walters, and Dana Rohrabacher (who had been elected to fifteen terms) were all defeated. Democrats also picked up two open seats previously held by retiring GOP incumbents: thirteen-term incumbent Ed Royce and nine-term incumbent Darrell Issa. The seven Democratic House pickups in California were the most made by the party in the 2018 election cycle.
^112 campaigning Democratic candidates. Suspended campaign: Dotty Nygard (District 10); Aja Brown (District 44); Michael Kotick, Laura Oatman, and Rachel Payne (District 48). Although she suspended her campaign, Brown did advance to the general election.[1][2]
^No ballot access: American Solidarity Party, K9 Party, and Socialist Equality Party. Brian T. Carroll (ASP, District 22), Robert Pendleton (K9, District 49), and Kevin Mitchell (SEP, District 51), appear on ballot as "No party preference."[5]
The 1st district is based in inland Northern California and includes Chico and Redding. Incumbent Republican Doug LaMalfa, who had represented the 1st district since 2013, ran for re-election. He was re-elected with 59.1% of the vote in 2016. The district had a PVI of R+11.
After advancing to the general election, Democratic candidate Audrey Denney was forced to pause her campaign for emergency tumor-removal surgery in August,[12] but returned in time to debate LaMalfa in September.[13]
The 2nd district is based in California's North Coast and includes Marin County and Eureka. Democrat Jared Huffman, who had represented the 2nd district since 2013, ran for re-election. He was re-elected with 76.9% of the vote in 2016. The district had a PVI of D+22.
The 3rd district is based in north central California and includes Davis, Fairfield, and Yuba City. Democrat John Garamendi, who had represented the 3rd district since 2013 and had previously represented the 10th district from 2009 to 2013, ran for re-election. He was re-elected with 59.4% of the vote in 2016. The district had a PVI of D+5.