A Republican senator who has been one of Donald Trump’s biggest obstacles through twin GOP congressional majorities just announced that he is ending his opposition to the nomination of Kevin Warsh to be the next chair of the Federal Reserve. Thom Tillis of North Carolina made the announcement Sunday on NBC’s Meet the Press , handing the administration a much-needed win at a moment where the president’s Cabinet appears to be in flux and under scrutiny for bad behavior. Tillis told NBC’s Kristen Welker that his opposition was no longer necessary after he received assurances from the Department of Justice around its now-halted efforts to go after the current Fed chair, Jerome Powell, with a criminal investigation surrounding renovations to the agency’s headquarters. That probe was viewed by many of the White House’s critics, Tillis included, as an attempt to put political pressure on Powell to resign or otherwise bend to Trump’s will.…