"I absolutely spoke to the President, whether he realized it was an interview, I don't know... not off the record", Wolff said, adding "I spoke to people who spoke to the President on daily, sometimes minute by minute basis".
For example, the book leads the reader to believe that Trump likes to be in bed by 6.30pm with a cheeseburger while watching three televisions simultaneously.
The book, "Fire and Fury: Inside the Trump White House", was available first thing Friday after the publisher moved up the release date amid the heightened attention.
The book includes reporting that Trump never wanted to be president, quotes from some of Trump's advisers insulting the president's intelligence and saying that he frequently repeats himself in conversation. Assistants - young women in the Trump uniform of short skirts, high boots, long and loose hair - as well as, in situation-comedy proximity, all the new stars of the show: Steve Bannon, Kellyanne Conway, Reince Priebus, Sean Spicer, Jared Kushner, Mike Pence, Gary Cohn, Michael Flynn (and after Flynn's abrupt departure less than a month into the job for his involvement in the Russia affair, his replacement, H.R. McMaster), all neatly accessible.
"They thought - and there is a real question as to why they thought this - that they were gonna get a fair shake from Michael Wolff".
Secretary of State Rex Tillerson, who is one among top administration officials to have spent the most time with Wolff, however ridiculed any negative impression about Trump's mental health. Demand for the book has been insatiable since reports of its contents emerged Wednesday.
He said the White House's reaction to the book's release has been all wrong, including threatening to sue the publisher to block it from coming out. "He used Sloppy Steve Bannon, who cried when he got fired and begged for his job".
Wolff's book also claims President Trump eats McDonald's because he fears being poisoned.
In Washington, D.C., people waited outside bookstores in extremely cold weather to buy the book.
Wolff went on to say that he has recordings of some of those conversations.