Joe Biden officially earned the endorsement of the firefighters union Monday, putting in his corner a powerful organizing force that stayed on the sidelines of the 2016 race. The executive board of the International Association of Firefighters met and voted to ratify its endorsement of the former vice president within hours of his formal entry into the race on Thursday. The union had warmly welcomed Biden to their annual Washington convention last month with signs of “Run, Joe, Run!” General President Harold Schaitberger made the endorsement official in an online video. “Joe’s a lot like our firefighters. He's a problem...