Rep. Brad Sherman (D-Calif.) defeated fellow Democratic Rep. Howard Berman in their member-vs.-member match-up.
It was a nasty campaign, with the two lawmakers almost coming to blows during a debate and having to be separated by a police officer.
The redistricting process put the two men in the same seat, which contained much of Sherman's old territory. Under California's new primary system, the top two vote-getters, regardless of party, move on to the general election.
Democratic leadership indicated a preference for Berman, with Rep. Steny Hoyer (D-Md.), the No. 2 in leadership, endorsing him. Berman also had the endorsement of prominent Republicans like Sens. John McCainJohn McCainNunes endures another rough day GOP lawmakers defend Trump military rules of engagement Senate backs Montenegro's NATO membership MORE (R-Ariz.) and Lindsey GrahamLindsey GrahamNunes endures another rough day Senate backs Montenegro's NATO membership Senate about to enter 'nuclear option' death spiral MORE (R-S.C.), who cited his work on the House Foreign Affairs Committee.
Sherman, meanwhile, had the support of former President Clinton.
—This story was updated at 5:28 a.m.