US President Donald Trump has replaced his acting chief of staff, Mick Mulvaney, whose departure had long been rumoured.
He said North Carolina lawmaker Mark Meadows would take over the job, a development tipped for weeks.
Mr Trump said Mr Mulvaney would become US special envoy to Northern Ireland.
Mr Mulvaney was perceived to have implicated the president in last year’s impeachment inquiry in an off-the-cuff remark at the White House podium.
When Mr Mulvaney gave a rare White House press conference in October, he shrugged off criticism over an alleged corrupt deal with Ukraine by saying: “We do that all the time.”
Mr Trump was reportedly outraged by the gaffe.
Mr Mulvaney then walked back his comments in a written statement that said: “Let me be clear, there was absolutely no quid pro quo between Ukrainian military aid and any investigation into the 2016 election.”
Last month, Mr Trump said reports that Mr Mulvaney would be fired were “false”, insisting he had a “great relationship” with him.
Despite his lofty White House role, Mr Mulvaney was never part of the Trump inner circle.
Shortly after he was picked to be chief of staff in late 2018, video emerged of Mr Mulvaney making a disparaging remark about Mr Trump.
He had said in 2016: “Yes, I am supporting Donald Trump, but I’m doing so despite the fact that I think he’s a terrible human being.” He had also said Mr Trump was “just as bad” as his opponent, Hillary Clinton.
Mr Meadows is retiring from the House of Representatives where he led the Freedom Caucus, a rump of hardline conservative lawmakers.
In Friday night’s tweet Mr Trump said: “I have long known and worked with Mark and the relationship is a very good one.”