The author of an “expose” on Donald Trump has said many people close to the President describe him as a “moron, an idiot” and “like a child”.
Michael Wolff spoke out after Mr Trump said his book was “full of lies”.
US publishers Henry Holt & Co brought forward the release date by four days after the US President’s legal team attempted to block the publication, and bookshops have reported people queuing up outside.
Little, Brown has done the same in the UK because of “unprecedented demand”.
Wolff joked: “Where do I send the box of chocolates?”
In an interview with NBC News’ Today talk show, he said: “I will tell you the one description that everyone gave, everyone gave, everyone has in common. They all say he is like a child.
“And what they mean by that is he has a need for immediate gratification. It’s all about him…they say he’s a moron. An idiot.”
Asked if he had interviewed the President about the book, Wolff replied: “I absolutely spoke to the President.
“Whether he realised it was an interview or not, I don’t know, but it certainly was not off the record.”
Wolff said he spoke to Mr Trump after his inauguration and “spent about three hours with the President over the course of the campaign in the White House, so my window into Donald Trump is pretty significant”.
He added: “I spoke to people who spoke to the President on a daily, sometimes minute-by-minute basis.”
The book, Fire And Fury: Inside The Trump White House, caused a storm of interest when excerpts were released.
There was a queue at the door at midnight at one bookshop in Washington DC, which reportedly sold all its copies in less than 20 minutes.
One buyer said: “I think a lot of people are interested because it blew up so quickly. Everyone has heard about it.”
The book includes alleged accounts of how the President lives and what his colleagues think of him.
In the book, Wolff claims Mr Trump’s former ally and chief strategist Steve Bannon questioned his fitness for office.
Mr Bannon, who was sacked by Mr Trump in August, is also quoted as saying a meeting between Mr Trump’s son, Don Jr, and a group of Russians was “unpatriotic” and “treasonous”.
Around an hour before the book went on sale, the President tweeted: “I authorized Zero access to White House (actually turned him down many times) for author of phony book!
“I never spoke to him for book. Full of lies, misrepresentations and sources that don’t exist.
“Look at this guy’s past and watch what happens to him and Sloppy Steve!”
According to the book, the President is regarded as an “idiot” by treasury secretary Steve Mnuchin and former chief of staff Reince Priebus.
Wolff writes that chief economic adviser Gary Cohn labelled the President “dumb as s***”, while national security advisor H.R. McMaster allegedly considers him a “dope”.
The book also claims to reveal an insight into Mr Trump’s bedroom habits.
He and Melania are said to have separate bedrooms; Mr Trump has three TV sets in his; he strips his own bed; and the President prefers going to his room at around 6.30pm to watch his screens and call friends.
Wolff also alleges Mr Trump did not want to win the 2016 election because he thought losing could offer “a far more powerful brand and untold opportunities”.
However, the White House rubbished the book, with press secretary Sarah Huckabee Sanders dismissing it as “ridiculous”.
She added that Mr Trump and his family “would not have put themselves through” the campaign if they did not believe they could win, or want to win.
The President immediately distanced himself from Mr Bannon as the allegations started to emerge on Thursday, saying: “Steve Bannon has nothing to do with me or my presidency.
“When he was fired, he not only lost his job, he lost his mind.”
The President’s legal team sent a “cease and desist” letter to Wolff and his publisher, threatening libel action.
Here are some of the book’s most striking claims: