LOS ANGELES — It’s a labor dispute that had drawn little notice, affecting about 150 workers and featuring only a handful of picket lines. Yet in the heated political atmosphere surrounding the Democratic presidential contest, the impasse is now drawing outsized attention as it threatens to upend a nationally televised debate.
While few expect the dispute between cafeteria workers at Loyola Marymount University and a food services company to stop Thursday’s planned debate at the campus — negotiators returned to the bargaining table Monday night — the episode is the latest evidence of the hold organized labor still exerts over the Democratic Party’s leading presidential candidates. All seven candidates expected to participate pledged not to cross a picket line, even though there has been no strike and no immediate plans to hold one.
Their solidarity with the local union here concludes a year in which Democratic candidates have made a show of proclaiming their support for organized labor — joining autoworkers demonstrating in Michigan and supporting strikes by public-school teachers — as they court one of the party’s most important constituencies.
“I’ve never seen an election where the candidates are walking picket lines, consistently talking about federal labor law, and being seen with union members as much as they can,” said Peter Dreier, a professor of politics at Occidental College in Pasadena. “Over the last decade or so labor unions have been making a comeback with much more visibility, more activism. Even though the unions haven’t gained many more members, they’ve definitely won a lot more support.”
The troubles began last Thursday when Sodexo, the company that has the contract to operate dining halls on the Loyola Marymount campus, put a temporary halt to contract negotiations with Unite Here Local 11, which represents the cafeteria workers. According to union officials, Sodexo said it would restart talks in January after the holiday season.
But that would have deprived the union of using the debate as leverage. So by Friday afternoon, Unite Here Local 11, which is affiliated with the powerful Culinary Workers union that represents casino employees in Las Vegas, had extracted statements from all seven candidates saying they would not cross a picket line to debate at Loyola Marymount.
The move worked. The chairman of the Democratic National Committee, Tom Perez, a former labor secretary, spent the weekend speaking with management from Sodexo and officials from the local union at Loyola Marymount. He is scheduled to arrive in Los Angeles on Tuesday morning and has offered to personally negotiate with the union and Sodexo.
Also involved in the talks are the chairman of the California Democratic Party, Rusty Hicks, and Mayor Eric Garcetti of Los Angeles.
The two sides are set to continue negotiations on Tuesday, according to officials familiar with the situation.
“We’re optimistic for a positive resolution so the American people can hear from our presidential candidates on a brighter, better vision for our nation,” Mr. Hicks said.
A Sodexo spokesman, Enrico Dinges, said the company was “100 percent committed’’ to reaching an agreement. Mr. Dinges said “any statement that we have left the bargaining table is not accurate.”
Senators Bernie Sanders and Elizabeth Warren were the first candidates to publicly pledge solidarity with the cafeteria workers on Friday, demonstrating the unique grip labor unions hold on California politics. In recent years, the state’s unions have called strikes that have shut down Hollywood, public schools and hospitals.
State lawmakers in 2016 approved a statewide $15 minimum wage and, earlier this year, created some of the most stringent laws declaring that contract workers such as Uber drivers should be classified as employees. The agency that oversees its public employee retirement program, known as Calpers, is the nation’s largest public pension fund.
Given the influence unions wield in the state, showing solidarity with workers is important for any Democrat who hopes to win California’s delegate-rich primary on Super Tuesday in March.
Thursday’s debate, in fact, is only taking place at Loyola Marymount because the Democratic committee’s first choice as host, the University of California Los Angeles, is enmeshed in a labor dispute of its own.
The powerful AFSCME union, which represents public employees, has been battling the University of California system for three years over outsourcing on campuses and medical centers. Soon after announcing U.C.L.A. as the debate host in late October, party officials announced they were searching for a new location in the Los Angeles area and eventually relocated to Loyola Marymount, about 15 minutes away.
The debate will take place against the backdrop of a historic vote in the House on whether to impeach President Trump. And it follows days of anxiety among Democrats about the dwindling number of participants on the stage. Of the seven candidates — the smallest number yet for a debate — all but one, Andrew Yang, will be white. The leading black and Latino candidates failed to qualify, leading to concern that the debate field won’t be representative of the electorate that will choose a nominee.
The gathering will also reflect a new order in the party’s nominating contest. Mayor Pete Buttigieg of South Bend, Ind., after charging to a lead in Iowa polls, has found himself under attack from Mr. Sanders and Ms. Warren. Mr. Sanders has also seen his stock rise in recent weeks as Ms. Warren has lost ground. Center stage will be occupied, as it has been throughout the fall, by former Vice President Joseph R. Biden Jr., who remains the leader in national polling.
So far this year, labor unions have largely stayed on the sidelines, waiting to see how the Democratic field shakes out. Only a few endorsements have been handed out as unions try to push candidates closer to their preferred positions.
Mr. Dreier, the Occidental professor, said he had not seen sentiments this supportive of labor unions from the Democratic field in decades, and he called Unite Here’s threat a “shot across the bow” for both Loyola Marymount and other universities that contract with Sodexo.
“They’re using this as a test of their strength,” Mr. Dreier said of the union. “This is a big coup for national attention.”
Labor officials in Los Angeles said the D.N.C. had been warned about the dispute long before last week. The union has been in negotiations with Sodexo since March and has occasionally set up picket lines at the school.
Ada Briceño, a co-president of Local 11, said Mr. Perez, the D.N.C. chairman, had been in touch with both the union and Sodexo.
“We don’t know the specifics, but we know that he’s trying to be helpful,” she said.
Ms. Briceño called Sodexo’s initial decision to postpone negotiations until January “a slap in the face.”
“We felt it was crucial to alert the candidates that this was a problem for us,” she added.
Since issuing their statements supporting the union on Friday, the candidates have been quiet about the dispute. Officials with several campaigns said Monday that they remained in the dark about the status of the dispute and expected the debate to proceed as planned.
At least two of the candidates planning to debate are already in California. Mr. Sanders attended a rally Monday night in the Coachella Valley east of Los Angeles, and Mr. Buttigieg attended fund-raisers in Northern California on Monday and had more planned for the Los Angeles area on Tuesday. The former housing secretary Julian Castro, who did not qualify for the debate, is also holding events in the Los Angeles area.
If the debate were canceled or moved to a different location, it would be a significant blow to Loyola Marymount, which operates largely in the shadows of larger Los Angeles campuses like the University of Southern California and U.C.L.A. University officials have been silent since Friday, when they released a statement urging Sodexo to meet with Local 11 to “advance negotiations and solutions.”
Despite the scramble, few Los Angeles political power-brokers think the debate will be scrapped. Mr. Garcetti, the mayor, issued a brief statement expressing his optimism.
“I am confident this can be resolved and hopeful that the debate can go ahead as scheduled,” he said.