Former national security adviser John Bolton shook up the Trump impeachment standoff Monday with his announcement that, if subpoenaed, he is “prepared to testify” before a Senate trial. It’s still not clear, of course, when or even if a trial might occur, since House Speaker Nancy Pelosi is withholding the articles of impeachment. But, if there is a trial, and if the Senate subpoenas Bolton, he won’t fight.

Senate Minority Leader Chuck Schumer has demanded the trial include witnesses. Schumer specifically wants the Senate to hear testimony from Bolton, current White House chief of staff Mick Mulvaney, and two other White House officials, Robert Blair and Michael Duffey.