The book, Fire and Fury: Inside the Trump White House, set off a political firestorm this week with its portrayal of Trump as not particularly wanting to win the U.S. presidency in 2016 and unprepared for the job.
Trump attempted to stop it from being released, saying he never gave Wolff access to the White House and the book is full of “lies, misrepresentations and sources that don’t exist.”
But the book officially released Friday at 9 a.m. ET and is already topping Amazon’s Best Sellers list.
WATCH: Trump team tries to halt publication of explosive book
Speaking on the Today show Friday, Wolff dismissed Trump’s claim that he had never spoken to the writer.
Wolff said he “absolutely” spoke to Trump and whether he “realized it was an interview or not, I don’t know, but it was certainly not off the record.”
Wolff then said he had records and notes of over 200 interviews with people in the White House, but did not say whether he would release tapes of the conversation.
“I have records, I have notes,” he said. “I am certainly in every way comfortable with everything I have reported in this book.”
Wolff said he wrote the book to get a sense of what it was like to work with Trump. And after interviewing many people who work with the president, Wolff said “100 per cent of the people around him” question his intelligence.
“They say he’s a moron, an idiot. Actually, there’s a competition to sort of get to the bottom line here of who this man is. This man does not read, he does not listen, he’s like a pinball just shooting off the sides,” he said.
“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,” he added.
Asked about Trump’s effort to stop the book’s publication, Wolff said the move only boosted the sales.
“Where do I send the box of chocolates?” he said.
White House fires back
White House spokeswoman Sarah Huckabee Sanders slammed the book during an appearance on Fox and Friends Friday morning. She said Wolff never interviewed Trump but repeatedly “begged to see the president.”
Sanders also called Wolff “a guy who made up a lot of stories to try and sell books.”
WATCH: Huckabee Sanders blasts ‘sad, pathetic’ new tell-all book
Speaking at a media conference Thursday, Sanders also described the book as “some trash” filled with “mistake after mistake.”
— With files from Reuters and the Associated Press