WASHINGTON – President Trump's lunch on Tuesday with Rex Tillerson might be a little tense given the president's latest volley in his feud with the secretary of State.

A week after reports that Tillerson once called Trump "a moron," the president told Forbes magazine:

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

That comment won't tap down speculation that Tillerson may depart the Trump administration.

Last week, Tillerson took the unusual step of making a televised statement to refute an NBC News report that he had considered resigning his post, and was so frustrated with Trump that he called him a "moron" during a July 20 meeting at the Pentagon. Trump later said he had total confidence in his top diplomat.

Defense Secretary James Mattis is also scheduled to attend the White House lunch; maybe he can help break the ice.