White House aides believed Mike Pence would support using the 25th Amendment to remove Donald Trump, a new book has claimed.

The bombshell claim - immediately denied by the Vice President's camp - has emerged in a book by an anonymous Trump official entitled 'The Warning'.

The official is the same one who wrote a New York Times op-ed in 2018 claiming to be 'part of the resistance' inside the Trump White House.

In the book, the author claims that White House staff made a 'back-of-the-envelope tally' in 2017 of who would be willing to plot against Trump.

According to HuffPost, they believed that Pence would sign off the procedure and take the acting presidency himself.

Last night his press secretary Katie Waldman labeled the allegation 'fake news'.

Claim: Vice President Mike Pence, pictured at Fort Hood in Texas last month, was expected to support the use of the 25th Amendment against Donald Trump, a new book claims

Under the 25th Amendment, Pence and a majority of the Cabinet could declare the President incapacitated and unable to discharge his powers.

Pence would then become Acting President with all the 'powers and duties' of the top job.

Trump could challenge their decision, setting up a constitutional stand-off in Congress where the House and Senate would decide the issue.

Revelations: The cover of 'A Warning', a new book by the same anonymous Trump official who wrote last year's New York Times op-ed

The procedure has never been used in that way, although Presidents Ronald Reagan and George W. Bush briefly triggered it themselves during medical surgery.

Rumors that it could be used against Trump have swirled in Washington since his early days in office.

According to the new book, entitled A Warning, White House staff discussed the matter in 2017 when James Comey was fired as FBI director.

Aides described Trump's behavior at the time as 'unhinged' and allegedly drew up a list of staff who might agree to remove him.

According to the author, there was 'no doubt in the minds' of senior staff that Pence would back such a move.

However, the discussions only took place informally and never led to a concerted plot against Trump.

In the New York Times op-ed, the same official said that 'no one wanted to precipitate a constitutional crisis'.

'We will do what we can to steer the administration in the right direction until one way or another it’s over,' they wrote.

Pence has positioned himself as a loyalist and denied that he or his staff had written the anonymous NYT column.

In the wake of the op-ed's publication he insisted he had 'never' been part of any discussion about the 25th Amendment.

The writer claimed to be part of a 'resistance' movement inside the White House, working behind the scenes to thwart Trump's most dangerous impulses.

Under fire: Aides of Donald Trump (pictured yesterday in Monroe, Louisiana) allegedly discussed his 'unhinged' behavior in his early months in office

The op-ed described the President as 'impetuous, adversarial, petty and ineffective' in the way he runs the government.

Trump reacted angrily to the work, calling it 'gutless' and a 'disgrace'.

'If the GUTLESS anonymous person does indeed exist, the Times must, for National Security purposes, turn him/her over to government at once,' he demanded.

The New York Times said the person's identity was known to them but said their job would be 'jeopardized' if it was made public.

The new book is described as offering a 'firsthand account of one of the most consequential presidencies in American history'.

It is due to be published later this month.

According to publishers, the author plans to donate a substantial portion of the royalties to non-profit organizations.

The literary agents behind the book also represented Comey and former White House aide Cliff Sims in their tell-all book deals.

White House press secretary Stephanie Grisham has already scorned the book, saying: 'Takes a lot of conviction and bravery to write a whole book anonymously.'

The 25th Amendment was passed in 1967 to clarify what would happen in case of emergency.

John F. Kennedy's assassination in 1963 had heightened fears of a vacant presidency at the height of the Cold War.

Vice Presidents George H.W. Bush and Dick Cheney each spent a few hours as Acting President while their bosses had colonoscopies.