All seven Democratic presidential candidates who met the qualifications to participate in next week’s debate declared their support on Friday for a local labor union and said they would not participate in the debate if they have to cross the union’s picket line.

UNITE HERE Local 11 sent a letter Friday to all the Democratic presidential campaigns informing them of a labor dispute involving their union on Loyola Marymount University’s campus, the site for next week’s debate. LMU subcontracts its food service operations to a company called Sodexo, and Local 11 has been in negotiations with Sodexo since March for a collective bargaining agreement, according to the letter. A resolution has not been reached and Sodexo last week canceled scheduled contract negotiations, according to the union.

After receiving the letter, the candidates — Elizabeth Warren, Bernie Sanders, Andrew Yang, Joe Biden, Pete Buttigieg, Tom Steyer and Amy Klobuchar — all announced their support of the union.