A dispute between a union and a service company could throw a monkey-wrench in next week’s sixth Democratic presidential debate in Los Angeles. Senator Amy Klobuchar and all five rivals who qualified for that debate say they’ll skip it, if an ongoing labor dispute at Loyola Marymount University would force them to cross picket lines. Klobuchar tweeted Friday, “I will not cross the picket line and will stand with UNITEHERE11 to fight for the dignity of work.” That union — representing cooks, dishwashers, cashiers and servers — says it’s been in negotiations with a service company since March.