Yale University psychiatry professor Dr. Bandy X. Lee in December told more than a dozen lawmakers President Donald Trump was "going to unravel, and we are seeing the signs."

Lee, who edited the book, "The Dangerous Case of Donald Trump," was invited to Capitol Hill to talk about Trump's behavior Dec. 5 and 6. She told Politico all the lawmakers in attendance were Democrats, except for one Republican senator, and that one senator "said that it was the meeting he most looked forward to in 11 years."

"Their level of concern about the president's dangerousness was surprisingly high," she added.

She told Politico that Trump was "going back to conspiracy theories, denying things he has admitted before, his being drawn to violent videos."

Lee also warned, "We feel that the rush of tweeting is an indication of his falling apart under stress. Trump is going to get worse and will become uncontainable with the pressures of the presidency."

Trump on Wednesday tweeted he has a "much bigger & more powerful" nuclear launch "button" than North Korean leader Kim Jong-Un, and a reporter afterward asked White House press secretary Sarah Huckabee Sanders if Americans should be "concerned about the president's mental fitness."

Medical practitioners have questioned Trump before, and the book Lee edited contained the opinions of 27 mental health practitioners as to why the president was mentally unstable.