President Donald Trump has removed a Democratic member of the U.S. National Labor Relations Board from office, an unprecedented move that will escalate an ongoing legal battle over the scope of the president's powers to control federal agencies.

President Trump has fired the lone Democrat on the National Labor Relations Board, leaving the country’s top arbiter of union issues without

Federal labor law explicitly limits removal of board members to instances of neglect or malfeasance. The termination is among several early moves Trump has made that push at the boundaries of executive authority.