President Donald Trump has described himself as a “very stable genius,” but economist and former Republican Bruce Bartlett believes that he’s anything but.

Writing on Twitter, Bartlett promotes a new piece he’s written for The New Republic that he says deeply examines the question of whether Trump is “too stupid to be president.”

In the piece itself, Bartlett notes that tales of Trump’s ignorance on policy matters have become legendary, and he says there is no evidence that things have improved over the last three-and-a-half years.

“From the earliest days of his administration, it has been obvious to everyone who has come in direct contact with him that Trump knows very, very little about any policy issue or even how the federal government operates. Among those most alarmed by Trump’s ignorance and incompetence were those in the military and intelligence community,” he writes. “After a National Security Council meeting on January 19, 2018, Defense Secretary James Mattis told aides that Trump had the understanding of ‘a fifth- or sixth-grader.'”

Bartlett then runs through a litany of both Trump advisers and foreign diplomats marveling at his colossal ignorance, including some aides who believe Trump doesn’t even understand that some foreign countries are in different time zones.

“With the Trump presidency, H.L. Mencken’s 1920 prediction that one day the White House ‘will be adorned by a downright moron’ has now come true,” Bartlett concludes.

Read the whole article here.