Steve Bannon questioned Trump's mental fitness while serving as his top aide, new book suggests

The White House has denied suggestions raised in a new behind-the-scenes book that Donald Trump lacks the mental capacity to do his job.

Asked about insinuations in Michael Wolff’s new tell-all work and more widely that Mr Trump was unfit to serve as President, Press Secretary Sarah Huckabee Sanders called them “disgraceful and laughable”.

“If he was unfit, he probably wouldn’t be sitting there and wouldn’t have defeated the most qualified group of candidates the Republican Party has ever seen,” Ms Sanders told reporters. “This is an incredibly strong and good leader”.

In Fire and Fury: Inside the Trump White House, Mr Wolff describes then-chief strategist Steve Bannon asking whether the 25th Amendment to the Constitution, which lays out the procedure for removing a President deemed “unable to discharge the powers and duties of his office”, might be invoked against Mr Trump, The Times reported.

Ms Sanders further described the work as “sad and pathetic”.

After Mr Trump unleashed a barrage of controversy with his equivocal response to an alleged white supremacist attack on demonstrators protesting a neo-Nazi rally, saying there was blame on “both sides,” Mr Bannon allegedly cited the 25th Amendment as the administration grappled with the fallout.

“The debate, as Bannon put it, was not about whether the president’s situation was bad, but whether it was 25th-Amendment bad,” Mr Wolff wrote.

Mr Bannon also discussed the possibility of Mr Trump not surviving his four-year term, noting the possibility of “a threat by the cabinet to act on the 25th Amendment”, according to The Times’ report.

“He’s not going to make it,“ Mr Woolf quoted Mr Bannon as saying. ”He’s lost his stuff.”

The release of excerpts from Mr Wolff’s book blasted open a chasm between Mr Trump and Mr Bannon.

In a statement effectively excommunicating his Mr Bannon the President in turn questioned his former aide’s sanity, saying when Mr Bannon was pushed out of the White House “he not only lost his job, he lost his mind”.

Opposition politicians have also mentioned the 25th Amendment while criticising Mr Trump.

Multiple Democratic members of Congress have couched their comments by invoking the measure, suggesting he was showing signs of mental instability and demanding that he undergo a psychiatric evaluation or be removed from office.

According to POLITICO, members of Congress last month summoned a psychiatry professor to come to Capitol Hill and brief them about Mr Trump’s behaviour.