In yet another bizarre indication that Donald Trump’s inner circle is fracturing more every day, the President has publicly challenged his secretary of state, Rex Tillerson, to an IQ contest.

The ‘mine’s bigger than yours’ taunt came in response to a question about Mr Tillerson reportedly calling Trump a “moron” at a national security meeting.

“I think it’s fake news,” Trump told Forbes magazine in an interview published overnight.

“But if he did that, I guess we’ll have to compare IQ tests. And I can tell you who is going to win.”

NBC News reported last week that Mr Tillerson called Mr Trump a “moron” during the meeting in July. It also said he had to be talked out of resigning.

Mr Tillerson later denied in a hastily called press conference that he’d considered resigning but did not directly address whether he’d called his president a moron. (A State Department official rejected the claim, but Tillerson still hasn’t.)

At the press conference, he parried the question by saying the issue of whether he called his boss a “moron” was “petty”. Clearly Mr Trump doesn’t agree.

If the gulf between Trump and Tillerson continues to grow and the secretary of state’s resignation ensues, the man who would pretty much decide on Trump’s choice of successor would be Senator Bob Corker.  He also copped a backhander from his president today.

The pair have been swapping insults on Twitter for days. Corker went further at the weekend, telling The New York Times that Mr Trump’s recklessness could bring on World War III.

Today the President hit back, using his preferred channel of communication – Twitter.

“The Failing @nytimes set Liddle’ Bob Corker up by recording his conversation. Was made to sound a fool, and that’s what I am dealing with!” Trump tweeted early Tuesday morning in the US.

The Failing @nytimes set Liddle' Bob Corker up by recording his conversation. Was made to sound a fool, and that's what I am dealing with!

— Donald J. Trump (@realDonaldTrump) October 10, 2017

Meanwhile, another national magazine overnight reported deepening rifts within the White House administration.

Vanity Fair claimed Mr Trump is growing increasingly frustrated with his chief of staff, John Kelly.

“They’re fighting a lot,” the magazine reported, quoting a “senior Republican close to the White House”.

Mr Kelly reportedly struggled to contain Trump’s rage after the Tillerson “moron” stories appeared last week and West Wing staff are increasingly discussing how long the retired general will last.

“He doesn’t love this job. He’s doing it as a duty for the country,” the magazine quoted “one person close to Kelly” as saying.