More than a dozen lawmakers last month met with a Yale University psychiatry professor for two days to discuss President Trump’s fitness for office, Politico reported Wednesday.

The Hill reports That a Dr. Bandy X. Lee met with the group of lawmakers on Dec. 5 and 6 and warned them the president is “going to unravel.” All of the lawmakers in attendance were Democrats, except for one Republican senator.

According to the doctor, the main concern comes from the president’s amount and capacity of tweets he sends out.

“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,” Lee told Politico.

Lee edited “The Dangerous Case of Donald Trump,” a collection released last October of testimonials from more than two dozen psychiatric experts assessing Trump’s mental state.

The White House has in recent weeks brushed aside questions about Trump’s physical and mental fitness.

Including White House Press Secretary Sarah Huckabee Sanders who went asked by a reporter if Americans should be “concerned about the president’s mental fitness,” after Trump tweeted that he has a “much bigger & more powerful” nuclear launch “button” than North Korean leader Kim Jong Un.

Sanders said there should be alarm, but not about the President’s words which are always marked by strength and a willingness never to back down. Instead, people should be concerned about Kim Jong Un’s mental health.

Some of the lawmakers used Trump’s tweet to renew discussions over the 25th Amendment, which allows for the vice president and the majority of the Cabinet to declare the president “unable to discharge the powers and duties of his office” and remove him. It has never been invoked.

In December, Trump was also appearing to slur his words during a speech announcing the U.S. would recognize Jerusalem as the capital of Israel.

The White House blamed the issue on a dry throat. Trump is scheduled for his first physical exam as president on Jan. 12. His military physician will make the results public.