Sen. Elizabeth Warren of Massachusetts; Sen. Bernie Sanders, I-Vt.; businessman Andrew Yang; former vice president Joe Biden; billionaire activist Tom Steyer; Sen. Amy Klobuchar of Minnesota and South Bend, Indiana, Mayor Pete Buttigieg said Friday they would refuse to cross picket lines in solidarity with Unite Here Local 11, which represents food service workers at the university who have been negotiating for a collective bargaining agreement.

“UniteHere11 is fighting for better wages and benefits – and I stand with them,” Warren tweeted Friday afternoon. “The DNC should find a solution that lives up to our party’s commitment to fight for working people. I will not cross the union’s picket line even if it means missing the debate.”

Sanders and Yang followed shortly afterward with their own vows.

“We must live our values and there is nothing more core to the Democratic Party than the fight for working people,” Yang tweeted.

Within a few hours, Biden, Steyer, Klobuchar and Buttigieg had followed suit with public statements in support of the union.

“I trust the DNC will find a solution ahead of the debate,” Steyer said.

The Democratic National Committee said it was working to find “an acceptable resolution” and alluded to chairman Tom Perez’s background as a former labor secretary.

“Tom Perez would absolutely not cross a picket line and would never expect our candidates to either,” DNC spokeswoman Xochitl Hinojosa said. “We are working with all stakeholders to find an acceptable resolution that meets their needs and is consistent with our values and will enable us to proceed as scheduled.”

Unite Here Local 11 represents 150 service workers – cooks, dishwashers, cashiers and servers – at the university, which subcontracts its food service operations to Sodexo.

The union has been in negotiations with Sodexo since March and began picketing on campus last month. In a statement, Susan Minato, the union’s co-president, said Sodexo had abruptly canceled scheduled contract negotiations last week.

“We had hoped that workers would have a contract with wages and affordable health insurance before the debate next week,” Minato said. “Instead, workers will be picketing when the candidates come to campus.”

The union had sent letters to the qualifying candidates’ campaigns Friday morning advising the candidates of the situation and warning that there could be picketing on the evening of the debate.

“Workers throughout Los Angeles struggle to survive in our city, where housing costs are skyrocketing and pushing more and more working people and their families toward housing insecurity or homelessness,” the letter stated. “Our members at LMU are no exception.”

Representatives for the DNC and Loyola Marymount University did not immediately respond to requests for comment.

This is the second time labor disputes have thrown a wrench into plans for the sixth Democratic debate, which was originally scheduled to take place at UCLA.

Because of stalled negotiations between the University of California system and AFSCME Local 3299, the DNC asked the debate co-hosts to “seek an alternative site” to UCLA and the debate was moved to Loyola Marymount.

Julián Castro, the former secretary of housing and urban development who did not qualify for the debate, also voiced his support for striking union workers and urged Loyola Marymount to “live up to its Jesuit values” in their negotiations.

“No candidate for the Democratic nomination should cross a picket line,” Castro tweeted.

The sixth Democratic debate, co-hosted by PBS News Hour and Politico, is scheduled for Thursday night.