Appearing to show frustration over reports that Rex Tillerson called him a “f******” moron” in July, Donald Trump has challenged the Secretary of State to an IQ contest.

In an interview with Forbes magazine, published Tuesday, Trump said, “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.”

At a press appearance with one of Tillerson’s predecessors, Henry Kissinger, Trump denied that he had tried to demean the Secretary of State. “I didn’t undercut anybody. I don’t believe in undercutting people,” he told reporters, soon after he labeled a leading Senator who criticized him as “Liddle’ Bob Corker”.

See VideoCast: Trump’s Threats and Chaos Within the White House

Asked if he still had confidence in Tillerson, Mr. Trump said, “Yes”:

However, in the Forbes interview Trump again undermined Tillerson’s attempts at diplomacy to avert a crisis over North Korea’s missile and nuclear tests: “He was wasting his time.” The remark echoed tweets on each of the last two weekends dismissing the Secretary of State after he spoke of back-channel discussions.

See TrumpWatch, Day 261: Trump Threatens North Korea, Snubs Tillerson Again

Trump maintained, “”I’m not undermining. I think I’m actually strengthening authority.”

White House Press Secretary Sarah Huckabee Sanders tried to wave away the latest incident, “[Trump] made a joke. Maybe you guys should get a sense of humor and try it some that. Nothing more than that. He has full confidence in the Secretary of State.”

But CNN’s Jim Acosta cited a well-placed source that Trump was not trying out his sense of humor:

Trump Tries to Humiliate “Liddle’ Bob Corker”

Trump began his day with a series of tweets which included another attempt to humiliate GOP Senator Bob Corker of Tennessee, after the chair of the Foreign Relations Committee publicly questioned Trump’s stability and warned of “World War III” if the President was not contained.

Trump falsely claimed that Corker — who hit back with a viral tweet on Sunday, “It’s a shame the White House has become an adult day care center” — was tricked by the New York Times in his subsequent remarks of concern:

Trump considered Corker as Secretary of State after the 2016 election, but reportedly told associates that the 5-foot-7 senator was too short for the post.

The attempted humiliation is a risky political strategy. Although he is not running for re-election in 2018, Corker is a key vote in a Senate with a slim 52-48 Republican majority. An immediate test will be Congress’s consideration of renewed sanctions on Iran if Trump decertifies Iranian compliance with the July 2015 nuclear deal — Corker oversaw the debates on the agreement — but the President is also risking his tax bill, after more than eight months in which the Administration has not had a single major legislative victory.

See TrumpWatch, Day 262: Trump’s Attack on GOP Senator Corker Backfires

Trump Blasts Non-Existent Reports that Kelly to Resign

Trump closed the day by lashing out at spectral reports that former general John Kelly, who became Chief of Staff in late July to bring some order to the White House, is about to resign:

There were no such claims in the mainstream US press yesterday, although Russia’s Sputnik News eagerly circulated Trump’s response.