Secretary of State Rex Tillerson. AFP A spokesperson reportedly said that Secretary of State Rex Tillerson had a "high IQ" after President Donald Trump offered to compare IQ tests.

State Department spokesperson Heather Nauert's statement on Tuesday follows an NBC News report that alleged Tillerson had called Trump a "moron" in a meeting earlier this year, and a subsequent interview with Forbes, where Trump called NBC News' report "fake news."

"I think it's fake news, but if he did that, I guess we'll have to compare IQ tests," Trump said in Forbes. "And I can tell you who is going to win."

On Tuesday afternoon, Trump and his staff appeared to walk back his previous comments and addressed the IQ fiasco: "I didn't undercut anybody, I don't believe in undercutting people," Trump said to reporters.

White House press secretary Sarah Huckabee Sanders added that Trump's statement was made in jest: "The president certainly never implied that the secretary of state was not incredibly intelligent," Sanders said, according to Politico. "He made a joke, nothing more than that."

Mensa, an organization that characterizes itself as a "high IQ society," offered to administer an IQ test to the two leaders, following the spat.

"American Mensa would be happy to hold a testing session for President Trump and Secretary Tillerson," Charles Brown, the group's communications director, said in The Hill.