Updated at 9 p.m. ET

For the fourth time in three years, President Trump has a new chief of staff.

With his administration grappling with the response to coronavirus — and just months ahead of the next election — Trump tweeted on Friday night that congressional ally Mark Meadows will be his newest top aide at the White House.

Meadows replaces Mick Mulvaney, who like him, was once part of the House Freedom Caucus. Meadows has come to be one of Trump's closest allies on the Capitol Hill, speaking with him regularly and helping the president keep Republicans in line. He was a staunch defender during Trump's impeachment trial.

Mulvaney lasted a little more than a year in the job, and never was able to get the "acting" removed from his title. He became tangled in the Ukraine scandal that led to Trump's impeachment when he put a temporary hold on military and other aid for Ukraine earlier this year at Trump's request.

But it's not all bad news for Mulvaney. Trump tweeted he would join the diplomatic ranks, becoming the U.S. special envoy for Northern Ireland.

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