'We've put our man on top': Trump on Mohammed bin Salman in Wolff's bombshell book

Trump alleged he installed Mohammed bin Salman as Saudi Arabia's crown prince, according to Wolff's publication Fire and Fury: Inside the Trump White House, which based on interviews with Trump's senior aides.

"We've put our man on top," Trump is said to have claimed to friends.

The shake-up in June saw Saudi Arabia's King Salman shelve decades of custom within the royal family, by naming his 31-year-old son Mohammad bin Salman as crown prince, ousting his nephew Mohammad bin Nayef. 

When the announcement came, Trump congratulated bin Salman on his "recent elevation".

Just a month earlier, the US president visited the kingdom in his first overseas trip, signing a multi-billion dollar arms deal with Saudi leaders.

In the book, Wolff described the trip as a "get-out-of-Dodge godsend", as Trump left Washington shortly after firing FBI Director James Comey.

"There couldn't have been a better time to be making headlines far from Washington. A road trip could transform everything."

On Friday, the US president faced a fresh public relations crisis with Wolff's publication, after his lawyers failed to block its release.

Fire and Fury: Inside the Trump White House depicts Trump as mentally unstable and in over his head, quoting key Trump aides expressing serious doubt about his fitness for office.

The book's publication was moved forward by four days, in response to a cease-and-desist letter from Trump.

The US president denied the allegations made in the book, which he described as full of "lies" and "misrepresentations". 

The book includes extensive quotes from Steve Bannon, the US president's former chief strategist, who also received a "cease and desist" order from Trump's attorneys.

"Look at this guy's past and watch what happens to him and Sloppy Steve!" Trump wrote - a possible reference to Bannon or Steve Rubin, the publisher of Wolff's book.

"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," Trump's lawyers said in the letter to Wolff.

In the book, excerpts of which were published this week, Bannon is quoted accusing Trump's eldest son Don Jr of "treasonous" contacts with a Kremlin-connected lawyer, and saying the president's daughter Ivanka, who imagines running for president one day, is "dumb as a brick."

Criticism from aides

But it is Trump himself who is cast in the most unfavourable light by a series of his top aides.

The book claims that for "Steve Mnuchin and Reince Priebus, the president was an 'idiot.' For Gary Cohn, he was 'dumb as shit.' For H.R. McMaster, he was a 'dope.' The list went on."

White House issued a scorched-earth dismissal of the book, its author and his sources.

"I don't think (Americans) really care about some trash that an author that no one had ever heard of until today, or a fired employee, wants to peddle," said White House press secretary Sarah Sanders, calling the book "complete fantasy."

Behind the scenes, though, Trump has been enraged by the betrayal by Bannon - a man who engineered the New York real estate mogul's link to the nationalist far right and helped create a pro-Trump media ecosystem. 

"He called me a great man last night. He obviously changed his tune pretty quick," Trump said in the White House's Roosevelt Room on Thursday.

Sanders suggested that Bannon's employer, Breitbart News, should consider firing him.

Fire and Fury: Inside the Trump White House depicts Trump as mentally unstable and in over his head, quoting key Trump aides expressing serious doubt about his fitness for office

Russia allegations

He wasn't fired, but Bannon's main financial backer is formally cutting ties with him, The Washington Post reported.

"I support President Trump and the platform upon which he was elected," the newspaper quoted billionaire conservative donor Rebekah Mercer as saying.

Her family has had no contact with Bannon for months, nor has it given money to support his political agenda, "nor do we support his recent actions and statements," she was quoted as saying.

Bannon, who left the White House in August, is also quoted in the book as saying that the investigation by special counsel Robert Mueller into Russian interference in the 2016 election will focus on money laundering.

The investigation by Mueller, a former FBI director, is looking into whether the Trump campaign colluded with Russia to help get him elected - a charge the president has repeatedly and vehemently denied.

Russia-related allegations in the book also ensnare Don Junior, who took a meeting with Russian lawyer Natalia Veselnitskaya in June 2016 after an intermediary promised material that would incriminate Trump's Democratic rival Hillary Clinton.

Trump's son-in-law Jared Kushner and then campaign chairman Paul Manafort also attended the meeting at Trump Tower in New York.

"The three senior guys in the campaign thought it was a good idea to meet with a foreign government inside Trump Tower in the conference room on the 25th floor - with no lawyers," Bannon was quoted as saying in the book.

"Even if you thought that this was not treasonous, or unpatriotic, or bad shit, and I happen to think it's all of that, you should have called the FBI immediately," he said.

Agencies contributed to this report