(CNN) A dozen lawmakers from the House and Senate received a briefing from Yale psychiatrist Dr. Bandy X. Lee on Capitol Hill in early December about President Donald Trump's fitness to be president -- and Lee has been asked to speak with additional lawmakers, worried about the President's mental state, later this month.

"Lawmakers were saying they have been very concerned about this, the President's dangerousness, the dangers that his mental instability poses on the nation," Lee told CNN in a phone interview Thursday, "They know the concern is universal among Democrats, but it really depends on Republicans, they said. Some knew of Republicans that were concerned, maybe equally concerned, but whether they would act on those concerns was their worry."

The briefing was previously reported by Politico . Lee, confirming the December 5 and 6 meeting to CNN, said that the group was evenly mixed -- with House and Senate lawmakers. And included at least one Republican -- a senator, whom she would not name.

Lee's public comments are highly unusual given protocols from medical professional organizations -- including the 37,000-member American Psychiatric Association -- banning psychiatrists from diagnosing patients without a formal examination. Under recent guidance from the APA, i t is "fine for a psychiatrist to share their expertise about psychiatric issues in general," but "member psychiatrists should not give professional opinions about the mental state of someone they have not personally evaluated," according to an APA blog post. When asked by CNN about Lee's comments, the APA referred them to this guidance.

Yale declined to weigh in on Lee's remarks when reached by CNN for comment.

"Yale University does not take positions or issue statements regarding the health or medical condition of public officials. However, the University will not interfere with the free expression or academic freedom of faculty members who wish to express their opinions in their areas of expertise or otherwise," Yale spokeswoman Karen Peart said in a statement.

Lee made it clear that she is not in a position to diagnose the President, or any public figure, from afar. But she said that it is incumbent on medical professionals to intervene in instances where there is a danger to an individual or the public. She argues that signs the President has exhibited have risen to that level of danger.

CNN has reached out to the White House for comment on Lee's remarks on Trump's mental health. During the White House briefing Thursday, press secretary Sarah Sanders called questions about the President's state of mind "disgraceful."

"If he was unfit, he probably wouldn't be sitting there, wouldn't have defeated the most qualified group of candidates the Republican Party has ever seen," Sanders said, before praising Trump as an "incredibly strong" leader.

The meeting between Lee and members of Congress was set up through a former US Attorney with ties to Capitol Hill who approached Lee at the request of a "number of lawmakers," she said. Lee provided them a briefing based on her book on the subject. Dr. James Gilligan -- another psychiatrist -- an expert on studying and predicting violence, also made a presentation.

"Mr. Trump is showing signs of impairment that the average person could not see," Lee said. "He is becoming very unstable very quickly. There is a need for neuropsychiatric evaluation that would demonstrate his capacity to serve."

Lee is scheduled to hold another briefing at the home of Democratic Rep. Rosa DeLauro later this month with lawmakers on the same topic and is also scheduled to speak at Democratic Rep. Jamie Raskin's town hall in Maryland this month as well. Raskin has introduced a bill called the "Oversight Commission on Presidential Capacity Act," which would use the 25th Amendment of the Constitution to create a "body" to determine whether the President is unable to execute the powers and duties of his office.

Raskin, who attended Lee's presentation, told CNN's Jake Tapper on Thursday that Trump's behavior is "increasingly delusional" and there should be an independent body to evaluate his fitness.

"Of course we got big public policy crises going on right now," Raskin said on CNN's "The Lead with Jake Tapper." "We've got a gun violence crisis, we've got the tax bill -- which was bought and paid for by the Koch brothers and the Mercers -- so we got some serious stuff to deal with and instead we're caught up every day in what looks like the country debating the mental health of the president, so it's a very dangerous and unstable situation as a number of Republican senators have themselves observed."

No Republican has called publicly for an evaluation of the President's mental fitness.

Lee cited Trump's repeated referencing of conspiracy theories in his public statements as a troubling sign.

"As he is unraveling he seems to be losing his grip on reality and reverting to conspiracy theories," she said. "There are signs that he is going into attack mode when he is under stress. That means he has the potential to become impulsive and very volatile."

Specifically, Lee pointed to Trump's verbal aggressiveness and his boasting about sexual assault on the Access Hollywood tape that was revealed during the campaign. She accused the President of inciting violence at his rallies, and having an "attraction" to powerful weapons. Lee said his threats to ramp up military action and the taunting an unstable leader in North Korean Leader Kim Jung Un are all signs of the President being on the verge of a psychotic breakdown.

In Wednesday's White House press briefing, Sanders also dismissed a question about the President's mental health.

"I think the President and the people of this country should be concerned about the mental fitness of the leader of North Korea," she said.

Lee rejected claims that her research is any way politically motivated.

"I am uninterested in partisan politics, I have never registered for a political party," she said. "Ideology doesn't interest me."