Rep. Adam Schiff, D-Calif., said everyone in Congress is concerned with President Trump’s mental fitness for office, after a book and report were released last week that called his fitness into question.

“Well, look, I don't think anyone is particularly surprised by what has been revealed in the Wolff book in terms of the questions people working closest with the president have about his capacity to do the job,” Schiff, the ranking Democrat on the House Intelligence Committee, told CNN host Jake Tapper.

“I don't think there is anyone in Congress, frankly, of either party who does not concur at least privately with those observations and concerns. Certainly very few are willing to express them publicly in Congress, and I think that's to the detriment of our institution.”

In the tell-all book published Friday, Fire and Fury: Inside the Trump White House, author Michael Wolff wrote "100 percent" of people close to Trump that he interviewed concluded Trump was "incapable of functioning in his job." The claim was coupled with a report that emerged last week, revealing that lawmakers had met with a psychiatrist to question the president’s mental health.

In response, Trump refuted the claims and called himself “really smart” and a “genius” in a series of tweets sent early Saturday morning. Trump said his “two greatest assets” were his “mental stability and being, like, really smart.”

"I went from VERY successful businessman, to top T.V. Star," Trump continued, adding “ 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!” Trump tweeted in conclusion.

Content from the book led Trump to denounce Steve Bannon, Trump's former chief strategist, after it was revealed Bannon said unflattering things about Trump’s family.

Trump initially fired back, saying Bannon had "nothing to do with me or my presidency. When he was fired, he not only lost his job, he lost his mind."

The book’s integrity has been questioned by critics, who have pointed out several inconsistencies in Wolff’s reporting and White House press secretary Sarah Sanders on Wednesday pushed back against some of the allegations made in the book and called it “trashy tabloid fiction."