Demonstrators demanding a cease-fire in the Israel-Hamas war prompted California Democratic Party officials to cancel evening events during their state convention on Saturday “for the safety and security of our delegates.”

California Democrats have been meeting in Sacramento this weekend to consider candidate endorsements ahead of the March primary. That includes the state’s competitive U.S. Senate race featuring four Democrats, including three sitting members of the House of Representatives.

The convention was disrupted multiple times Saturday afternoon by demonstrators demanding a cease-fire in Gaza. Party officials had increased security for the weekend convention, requiring participants to be scanned and have their bags searched before entering the convention hall.

Following the afternoon session, a large crowd of demonstrators gathered at the hall. Sacramento police closed some roads near the convention center, but soon reopened them.

Saturday evening, shortly after voting ended party endorsements, Democratic Party spokesperson Shery Yang said the evening’s events had been canceled.

“Due to circumstances beyond our control, and for the safety and security of our delegates and convention participants, we are cancelling tonight’s caucus meetings, hospitality suites and VoteFest taking place at the convention center,” Ms. Yang said.

The cancellation overshadowed a strong showing by congresswoman Barbara Lee, who was the top vote-getter among delegates. While no candidate had the 60 percent of votes required to earn the party’s formal endorsement, the results were a boost of confidence for Ms. Lee’s campaign as she finished ahead of rivals who have so far bested her in public polling.

Adam Schiff, Katie Porter and Ms. Lee, as well as former tech executive Lexi Reese attended Saturday’s convention hoping to secure enough support to earn the party’s official endorsement. They are all vying for the seat now held by Senator Butler, who was appointed when longtime Senator Feinstein died in September. Ms. Butler is not running for the seat and will step down when her term expires in early 2025.

Mr. Schiff is widely seen as the front-runner, leading the candidates in fundraising and boasting a pack of influential endorsements, including the coveted blessing of former Speaker Pelosi. Public polling, generally, has Ms. Porter second and Ms. Lee third among the Democrats, with a large chunk of voters still undecided.

But on Saturday night, it was Ms. Lee who emerged with just under 41.5 percent of the vote, enough to edge Mr. Schiff who had 40.18 percent in preliminary results announced by the party. Ms. Porter finished third with just over 16 percent. A little more than 2 percent of delegates opted not to endorse a candidate. Ms. Reese only received three votes.

The results were not a surprise at a convention tending to attract the most progressive members of the Democratic Party. Saturday was no exception, as demonstrators calling for a cease-fire in Gaza showcased how the Israel-Hamas war has divided some in the Democratic Party.

Ms. Lee, known for being the lone vote against war in Afghanistan in the days following the September 11, 2001, terrorist attacks, is in the best position to benefit from that fracture. Delegates cheered Ms. Lee when she called for a cease-fire to conclude her remarks during the afternoon session.

“She showed real courage,” said Howard Egerman, a delegate who said he was voting for Ms. Lee to get the party’s endorsement.

Mr. Schiff finished second in part on the strength of his endorsements from elected officials, who appoint a large number of delegates to the convention.

Delegate Stacy Fortner said while she loves and appreciates Ms. Lee, she won’t support her for the Senate because of her age. Ms. Lee is 77, and Ms. Fortner fears she won’t be in the Senate long enough to gain the seniority required for leadership posts.

Ms. Fortner said she voted for Mr. Schiff, who is 63.

“I am tired of a junior senator from California. I want a ranking member in the Senate. I want a committee chair. And I’m not willing to wait two decades to get it,” she said.

An endorsement from the state Democratic Party can boost a campaign in a competitive primary, but it doesn’t necessarily signal how the wider electorate feels about the race as party delegates tend to be more liberal. In 2018, the state party endorsed a state senator,, Kevin de Leon, over Feinstein in the general election, though it did little to boost his candidacy. Feinstein won the general election handily.

Still, in a competitive statewide race, every endorsement helps.

“Even in the absence of an endorsement, to gain the support of some of the most loyal and active activist Democrats in the state — they are a force multiplier,” Mr. Schiff said. “They are totally in it. They knock on doors, they send postcards, they text, they are the kind of beating heart of the party.”

Earlier in the day, demonstrators disrupted a forum for the U.S. Senate candidates. A spokesperson for the protest described demonstrators as nearly 100 youth, workers and Democratic volunteers. Aylet Hasachar, one of the leaders of the cease-fire demonstrators, said they disrupted the convention because “most Democratic representatives are not respecting the very fierce desire” of constituents who want a cease-fire.

“What’s happening in Gaza right now is a genocide. And the Democrats are complicit in that,” Hasachar said.

Basem Manneh, who is of Palestinian heritage and attended Saturday’s convention wearing a “Team Palestine” T-shirt, left the afternoon session shaking his head about the protests. He said he believed what was happening on both sides of the war was “sickening,” but he did not like protesters disrupting the convention.

“Protest all you want, but not like this,” he said.