White House press secretary Sean Spicer has quit, reportedly in protest at a shake-up of the communications team.
Mr Spicer stepped down because he was unhappy with US President Donald Trump's appointment of a new communications director, the New York Times reported.
Combative Wall Street financier Anthony Scaramucci has been picked for the role that Mr Spicer partially filled.
Mr Spicer's press briefings were a cable news hit, but he withdrew from camera in recent weeks.
The shake-up comes as the White House faces inquiries into alleged Russian meddling in last year's US presidential election and whether Mr Trump's campaign team colluded with Moscow.
The New York Times reported that 45-year-old Mr Spicer "vehemently" disagreed with the appointment of Mr Scaramucci, which he believed to be a "major mistake".
The search for a new appointment began after Mike Dubke resigned from the communications director job in May.
Mr Spicer has been serving as both press secretary and communications director since Mr Dubke's exit.
On day one of the administration's taking power in January, Mr Spicer set the tone of his relationship with the press by bursting into the briefing room to berate journalists for their reporting of crowd numbers at Mr Trump's inauguration.
His proclivity for gaffes and garbling of his words, as well as making debatable assertions, soon saw Mr Spicer's name trending on Twitter.
Spicer's low points
- Inflating crowd sizes at Trump inauguration at first briefing
- His appearance, particularly his suits, reportedly criticised by Trump
- Saying Hitler never used chemical weapons and referring to Holocaust "centres"
- Butt of text message joke by adviser Steve Bannon about his weight
- Defending Trump "covfefe" tweet by saying it had hidden meaning
- Frozen out of meeting with the Pope in Rome, despite being devout Catholic
- Not invited to Paris for Trump visit
He was mercilessly lampooned on the topical comedy show Saturday Night Live, where Melissa McCarthy played him as a gum-chewing, loud-mouthed thug who brandished his lectern at reporters.
Mr Spicer became something of a punchline when he reportedly sought refuge by a hedgerow on the White House grounds to evade reporters' questions on the night Mr Trump fired the FBI director in May.
Mr Scaramucci, who has no previous experience in communications roles, is currently senior vice-president of the Export-Import Bank, a US government agency which guarantees loans for foreign buyers of American exports.
His last on-camera briefing was on 20 June, and there have been few since then.
Members of the media have accused the Trump administration of attempting to kill off the daily news conferences to avoid scrutiny.
What does Scaramucci say?
In an assured debut, Mr Scaramucci attended Friday afternoon's news conference to announce that Sarah Huckabee Sanders, formerly Mr Spicer's deputy, would step into his shoes.
"I love the president and it's an honour to be here," Mr Scaramucci said. "He is genuinely a wonderful human being."
"The president has really good karma."
Mr Scaramucci, who has no previous experience in communications roles, paid tribute to Mr Spicer as "a true American patriot" and "incredibly gracious".
"I hope he goes on to make a tremendous amount of money," he said.
Mr Scaramucci also apologised and said he had been "unexperienced" as he explained his previous criticism of the president.
In an August 2015 interview with Fox Business, he dismissed Mr Trump as a "hack" and "an inherited money dude" with "a big mouth".
A former member of the Trump transition team, Mr Scaramucci mistakenly suggested to the BBC in January that Elton John would play at the new president's inauguration. The singer promptly denied it.