Donald Trump's closest advisers believe he is “incapable of functioning in his job” as president, a controversial new book about his White House has claimed.
The US president is said to repeat stories word-for-word within 10 minutes and struggle to recognise old friends, according to an account by journalist Michael Wolff.
Mr Trump’s lawyers went into all-out attack on Thursday by writing a “cease and desist” letter demanding the publishers pull the book before its release next week.
They also announced legal action against Steve Bannon, the former Trump campaign chief and adviser, for defamation after he was quoted widely in extracts.
Mr Bannon attempted to soothe Mr Trump’s fury over his involvement in the book, calling him a “great man” who he was supporting “day in and day out”.
In turn, Mr Trump told reporters it was a “misnomer” to say the pair still talked and noted that Mr Bannon had “changed his tune pretty quickly” after his criticism became public.
The spectacular row has been dubbed the most vicious falling out between a president and a former aide in modern history.
On Thursday, more revelations emerged from the book Fire and Fury: Inside the Trump White House, which is based on interviews with more than 200 people.
Some of the most controversial claims were about the ability of Mr Trump, 71, to carry out the demands of the presidency.
Mr Wolff reported that Mr Trump was known to repeat the same three stories “word-for-word and expression-for-expression” in 10 minutes, down from 30 minutes in the past.
He also claimed that Mr Trump “failed to recognise a succession of old friends” while at his Mar-a-Lago resort in Florida for the new year break.
Mr Wolff wrote in The Holywood Reporter that having spent time with Trump aides and family members “my indelible impression … is that they all - 100 percent - came to believe he was incapable of functioning in his job”.
Sarah Sanders, the White House press secretary, said questions about Mr Trump’s suitability for office were “disgraceful and laughable” during a White House briefing.
She said: “If he was unfit he probably wouldn’t be sitting there having defeated the most qualified group of candidates the Republican Party has ever seen.”
Ms Sanders has previously called the book "trashy tabloid fiction".
Questions were also raised about Mr Wolff’s reporting, with some commentators raising eyebrows at sections of the book where whole chunks of conversations are quoted verbatim.
Mr Trump's attorney Charles Harder sent a letter to Mr Wolff and publisher Henry Holt and Co demanding no further confidential information is disclosed. The book is due to be published on January 9.
"Your publication of the false/baseless statements about Mr. Trump gives rise to, among other claims, defamation by libel, defamation by libel per se, false light invasion of privacy, tortious interference with contractual relations, and inducement of breach of contract," the letter to Mr Wolff read.
Mr Bannon was also sent a letter informing him of coming legal action, citing “disparaging statements and in some cases outright defamatory statements” he is said to have made to Mr Wolff.
It also emerged that the White House has banned staff from using personal mobile phones in the West Wing in an apparent attempt to cut down on leaks.
Sarah Sanders, the White House Press Secretary, said: "Starting next week the use of all personal devices for both guests and staff will no longer be allowed in the West Wing.
"Staff will be able to conduct business on their government-issued devices and continue working hard on behalf of the American people."
In the book, Mr Bannon is quoted as calling a meeting Mr Trump’s son Donald Jr had with the Russians “treacherous” and “unpatriotic” and saying his daughter Ivanka was as “dumb as a brick”.
Other claims in the book – which has been strongly rebutted by the White House – include that Mr Trump thought he would lose the election and dyes his hair.
Mr Bannon pledged his support to Mr Trump in his first public comments since the row erupted as he spoke on Breitbart News Tonight, broadcast on Sirius XM radio.
“The president of the United States is a great man. You know I support him day in and day out,” Mr Bannon said.
Mr Trump later said to reporters on Mr Bannon: "He called me a great man last night. So he obviously changed his tune pretty quick. I don’t talk to him ... that’s just a misnomer."
The legal action marks a new low point in the relationship between Mr Bannon, the man most credited with getting Mr Trump into the White House, and the president.
Mr Bannon joined the US administration alongside Mr Trump but left in August 2016 to campaign through his right-wing website Breitbart News after clashing with other aides.
The legal action comes the day after Mr Trump publicly disowned Mr Bannon after revelations from the book became public.
Mr Trump said Mr Bannon had “lost his mind” and “has nothing to do with me or my presidency”.
Other allegations have begun to emerge on Thursday from the book, which is not released until next week.
The book also claims that a string of senior Trump figures made disparaging remarks about the president’s intellect, often in the crudest terms.
Aides Steve Mnuchin and Reince Priebus allegedly believed he was an “idiot”, national security adviser HR McMaster thought he was a “dope” and economic aide Gary Cohn considered him “dumb as s***”, according to the book.
The White House hit back against the book in the strongest terms on Wednesday, issuing a blanket rebuttal and warning people not to believe the claims.
Wow, Just looked at the comments section on Breitbart. Wow. When Bannon has lost Breitbart, he’s left with . . . umm, nothing.— Donald Trump Jr. (@DonaldJTrumpJr) January 3, 2018
Sarah Sanders, the White House press secretary, said: “This book is filled with false and misleading accounts from individuals who have no access or influence with the White House.
“Participating in a book that can only be described as trashy tabloid fiction exposes their sad desperate attempts at relevancy.”
There are also political consequences to the fallout between Mr Trump and Mr Bannon, who has been running a campaign to defeat mainstream Republicans since leaving office.
Firebrand Republican candidates who had been endorsed by Mr Bannon in their quest to defeat more mainstream candidates for Congress seats distanced themselves from him.
Michael Grimm, who is considering running for a New York seat, tweeted:
My statement on President Trump’s comments and the remarks attributed to Steve Bannon in Michael Wolff’s upcoming book: pic.twitter.com/LqtnRhD1I3— Michael Grimm (@RealMGrimm) January 3, 2018
Kelli Ward, who is seeking to defeat mainstream Republicans for the Arizona senate seat, said: