At a forum in Los Angeles later this week, the majority of the leading Democrats running for president will be trying to woo the Service Employees International Union. Union members will be sure to ask candidates about their plans to strengthen labor protections and make it easier for workers to organize.

Against the backdrop of the ongoing union strike by GM autoworkers, at least eight of the Democratic candidates are set to attend the “Unions for All” summit. Unions have traditionally been linked with the Democrats, but many union members supported President Trump in 2016 because of his promise to bring back outsourced jobs. Democratic candidates are now trying to win those voters back.