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President Donald Trump on Saturday cited his resume and success as both a television personality and a businessman as proof that he is — and always has been — in great mental health.

Speaking at a wide-ranging, impromptu audience with reporters, Trump said he felt compelled to fire off several tweets defending his mental state after the publication of Michael Wolff's tell-all book, "Fire and Fury: Inside the Trump White House."

"I went to the best colleges or college .... I was a very excellent student," Trump said, before ticking through his resume.

In a series of tweets on Saturday morning, Trump insisted that he is a "very stable genius" and that critics were speculating about his mental health because claims that he had colluded with Russia were “proven to be a total hoax.”

“Actually, throughout my life, my two greatest assets have been mental stability and being, like, really smart,” the president said in a tweet.

While the White House and some Republicans in Congress have sought to downplay the seriousness and credibility of special counsel Robert Mueller’s probe, four members of Trump's transition team or Cabinet have been charged so far in the investigation.

Related: Wolff calls Trump least credible person who has ever walked on earth

Trump was asked Saturday to respond to reports that he had instructed White House lawyers to ask Attorney General Jeff Sessions not to recuse himself from the Russia investigation.

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"Everything I've done is 100 percent proper," Trump said. "That is what I do, is I do things proper."

He again denied having colluded with Russia or having committed any crimes.

Now that Russian collusion, after one year of intense study, has proven to be a total hoax on the American public, the Democrats and their lapdogs, the Fake News Mainstream Media, are taking out the old Ronald Reagan playbook and screaming mental stability and intelligence..... — Donald J. Trump (@realDonaldTrump) January 6, 2018

....Actually, throughout my life, my two greatest assets have been mental stability and being, like, really smart. Crooked Hillary Clinton also played these cards very hard and, as everyone knows, went down in flames. I went from VERY successful businessman, to top T.V. Star..... — Donald J. Trump (@realDonaldTrump) January 6, 2018

....to President of the United States (on my first try). I think that would qualify as not smart, but genius....and a very stable genius at that! — Donald J. Trump (@realDonaldTrump) January 6, 2018

Trump said in a tweet that his opponents were “taking out the old Ronald Reagan playbook and screaming mental stability and intelligence.”

During Reagan's second term, there was continued speculation about his state of mind. In 1994, five years after leaving office, Reagan publicly announced that he had Alzheimer’s.

Trump added in response to a reporter's question Saturday that he doesn't know Wolff but he felt "heartened" because some in the media had questioned the veracity of his insider-account of the early days in the Trump administration.

"I consider it a work of fiction and I think it's a disgrace that somebody is able to have something, do something like that," Trump said. "The libel laws are very weak in this country."

The president and congressional leaders spent the weekend at Camp David hammering out the details of the 2018 legislative agenda. He appeared with Republican leadership Saturday to discuss their progress.

Beforehand, John Kelly, Trump's chief of staff, told reporters that the retreat had been successful and that DACA, the Deferred Action for Child Arrivals program, had been a large focus of the meetings. Trump has left it up to Congress to renew the Obama-era program, which allows people who were brought to the United States illegally as children to remain in the country.

On Saturday, Senate Majority leader Mitch McConnell of Kentucky praised Trump for his leadership in 2017, saying it would be a "tough year to top" for Republicans.

"From a right-of-center point of view, 2017 was the most consequential in the many years that I've been here in Congress," McConnell said.

Trump said conversations at the Camp David summit touched on issues including infrastructure, military funding and welfare reform, and he promised a more bipartisan approach in the new year.

The president also credited his tough rhetoric toward North Korea as being instrumental in getting the two Koreas to the negotiating table to discuss the North's participation in the 2018 Winter Olympics, which will be held next month in PyeongChang, South Korea.

Related: A new year brings an increasingly isolated President Trump

Trump said South Korean President Moon Jae-in thanked him for adopting such a staunch position toward the North.

"I hope it works out, I very much want to see it work out between the two countries," Trump said.

"Without my rhetoric and without my tough stance — and it’s not just a stance, this is what has to be done, if it has to be done — that they wouldn’t be talking about Olympics, that they wouldn’t be talking right now."

A North Korean representative to the International Olympics Committee said Saturday that his country would most likely participate in the Winter Games, according to Japan's Kyodo News agency.