Secretary of State Rex Tillerson denied Friday that he has ever questioned Donald Trump's mental capacity to be President of the United States.

Reports emerged in October that Tillerson called Trump 'a f***ing moron' after a meeting with advisers last July.

But amid claims Friday from author Michael Wolff that '100 percent of the people around' President Donald Trump question his intelligence and fitness for office, Tillerson told CNN that he's not among them.

'I've never questioned his mental fitness,' Tillerson said. 'I have no reason to question his mental fitness.'

Wolff, however, said that even Jared Kushner and Ivanka Trump, the president's son-in-law and elder daughter, question his suitability for the Oval Office.

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'I've never questioned his mental fitness,' Secretary of State Rex Tillerson said Friday of President Donald Trump

Author Michael Wolff said Friday that '100 percent' of the people around Trump question his intelligence and fitness for office, with some calling him a 'moron' and an 'idiot'

To hide his failings from the public, Michael Wolff claims White House Communications Director Hope Hicks (left) hatched a plan last fall to have interviewers submit their questions to President Trump beforehand. They're seen aboard Air Force One in November

'They all say he is like a child. And what they mean by that is he has a need for immediate gratification. It's all about him,' Wolff said on the 'Today' show. 'They say he's a moron, an idiot.'

The suggestion from his sources, Wolff said, purportedly quoting Steve Bannon, is: 'He's lost it.'

Wolff's book 'Fire and Fury' is a political gossip page-turner that paints Trump as an imbecile and his top aides as uncomfortable

Wolff writes that Steve Bannon once openly suggested Trump was so mentally unfit for office that the U.S. Constitution's 25th Amendment might be needed to remove him.

The 25th Amendment allows for a majority of the president's cabinet, or 'such other body as Congress may by law provide,' to decide if an Oval Office occupant is unable to carry out his duties – and then to put it to a full congressional vote.

Shortly after Wolff appeared on 'Today' in New York, White House press secretary Sarah Huckabee Sanders went on 'Fox & Friends' to rebut him.

'It's absolutely outrageous to make these types of accusations and it's simply untrue, and sad that people are going and making these desperate attempts to attack the president,' said Sanders.

On Thursday she chided reporters who dared ask questions about Trump's mental acuity, calling the queries '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,' she insisted. 'This is an incredibly strong and good leader.'

Tillerson reportedly called Trump 'a f***ing moron' following a meeting last summer, but now seems comfortable with the commander-in-chief's mental faculties

Former White House chief strategist Steve Bannon suggested Trump's cabinet and Vice President Mike Pence might have to use the Constitution's 25th Amendment to remove the president from power, according to Wolff

Tillerson has never denied making the 'moron' comment, only telling reporters that he was 'not going to deal with petty stuff like that.'

The president, however, called it 'fake news' – and joked that he would 'have to compare IQ tests' with his top diplomat.

But congressional Democrats invited a Yale psychiatrist to provide them with an assessment of the president's cognitive state last month.

And Wolff claimed Thursday in a Hollywood Reporter essay that Trump is increasingly forgetful, repeating stories word-for-word inside 10 minutes and failing to recognize old friends.

'At Mar-a-Lago, just before the new year, a heavily made-up Trump failed to recognize a succession of old friends,' he writes.