WASHINGTON (Reuters) - U.S. President Donald Trump has been fielding suggestions from allies on who might succeed his acting chief of staff, Mick Mulvaney, amid frustration at his team's response to the Democrats' impeachment inquiry, two sources close to the White House said on Monday.

Trump's irritation at being dogged by a variety of issues - from impeachment to his decision to move U.S. troops out of northeastern Syria - was on display on Monday in the White House Cabinet Room as the president aired his grievances at length before his senior advisers and a group of reporters.