"This is a guy who made up a lot of stories to try to sell books", Ms Sanders said in an interview on Fox News Channel.
On Wednesday, excerpts blew open a feud between Trump and his former adviser Steve Bannon, who is quoted extensively and unflatteringly describing Trump, his family and advisers. The book also attributes statements to him denigrating the President.
"They all say he is like a child", he said. According to the president, he never even gave him a quote. "When he came in he was very very pleasant".
Asked whether concerns about his mental state were serious, Mrs May said: "No".
But while several analysts, as well as Trump allies, questioned the veracity of some of Mr Wolff's claims, the controversy has increased pressure on Mr Trump, particularly in relation to comments attributed to Bannon about the Russia investigation.
"I'm getting calls daily of people ordering a copy on our website and asking me to hold a copy of the books that will arrive on Tuesday", said Jennings. So far, Wolff has stood by his reporting.
In another section of the book, Wolff writes that Nunberg struggled to explain the Constitution to Trump. "I've never had such conversation in the White House, outside of the White House, with Jared Kushner, with anybody else", Blair said in the interview.
So if Mr. Trump didn't want to be president, why did he collude with the Russians?