Sanders zeroed in on labor throughout his sprint across the state. He spoke at a meeting held by the Pennsylvania Association of Staff Nurses and Allied Professionals and talked up his pro-union bona fides at a Fox News-hosted town hall held in the shadows of a former steel mill. A former worker at an Erie-based locomotives manufacturer that recently held a strike also spoke at Sanders’ Pittsburgh rally, which drew an estimated 4,500 people, according to his campaign.

Sanders’ team repeatedly has called attention to the Erie workers, attempting to show that he understands the symbolic power of what the union described as the “first major U.S. manufacturing strike of the Trump era.” During a town hall on CNN earlier this year, Sanders admonished the manufacturing company for handing out lavish bonuses to executives while lowering wages. The leader of their union, United Electrical, Radio & Machine Workers of America Local 506 President Scott Slawson, also spoke at Sanders’ campaign kickoff rally in Brooklyn in March.

Recent polls show that significant numbers of Democratic voters prefer a contender who can win over one who shares their ideology. If Biden jumps into the presidential race, Sanders will need to prove to voters that he’s better equipped to take on Trump in Pennsylvania than the fellow labor ally.