OAKLAND, Calif. — The California Democratic Party snubbed Senator Dianne Feinstein on Saturday by handing its official endorsement and a badly needed boost to state Senator Kevin de Leon, her long-shot Democratic challenger.

In backing de Leon, a majority of the party’s 360-member executive board ignored Feinstein’s calls to stay neutral in the race. Her allies had warned an endorsement would create an intraparty squabble that could detract from important down-ballot races.

De Leon has long been courting party activists and appealed to those seeking a fresh face and a more progressive senator to fight against President Trump.

‘‘Today’s vote is a clear-eyed rejection of politics as usual in Washington,’’ de Leon said in a statement after the vote. ‘‘We have presented Californians with the first real alternative to the worn-out Washington playbook in a quarter-century.’’


A total of 217 delegates voted for de Leon, of Los Angeles, while 22 cast ballots for Feinstein and 94 voted for no endorsement.

Party members and activists are typically more liberal than the wider California electorate, which has sent Feinstein to Washington five times. Feinstein has turned skepticism from some party activists into an asset in her past campaigns.

The endorsement of de Leon means the state party will spend money promoting his candidacy this fall.

Still, Feinstein outpaces him in name recognition and cash and has a loyal following across California. She won the June 5 primary with 44 percent of the vote, compared to de Leon’s 12 percent.

Although it’s an embarrassment for California’s senior senator to lose her party’s official nod, it may do little to change the trajectory of the race.

‘‘We are confident that a large majority of California Democrats will vote to reelect Senator Feinstein in November,’’ Jeff Millman, her campaign manager, said Saturday night.

California runs a top-two primary system that sends the two highest primary vote-getters to the general election regardless of party. The system allowed de Leon to take the No. 2 spot by squeaking past a slew of unknown Republicans in the primary.


Six US House candidates for seats considered top Democratic targets joined Feinstein’s call for neutrality in a letter to members before the vote on Saturday.

‘‘A divisive party endorsement for US Senate would hurt all down-ballot candidates and our ability to turn out Democrats we desperately need to vote in November,’’ it said.

De Leon led the state Senate until earlier this year. He is the author of California’s sanctuary state law that was the target of a Trump administration lawsuit. A judge dismissed the case.

Feinstein was first elected to the US Senate in 1992, when she became the first woman to serve the state in that chamber. She is the ranking member of the Senate Judiciary Committee, where she will take center stage this summer during the US Supreme Court nomination fight.