"Michael Wolff is a total loser who made up stories in order to sell this really boring and untruthful book," President Donald Trump says about the author of "Fire and Fury."

He's not the only one to challenge assertions in the tell-all book, which has shaken the White House with accounts and quotes from current and former Trump administration officials.

New York Times White House correspondent Maggie Haberman, and several other journalists and Washington insiders, do as well.

"I believe parts of it, and then there are other parts that are factually wrong," Haberman said Friday on CNN. "He believes in larger truths and narratives. So he creates a narrative that is notionally true, that's conceptually true. The details are often wrong."

In one example, she pointed out that the book says Rupert Murdoch called Trump "a f-----g idiot," but in a column, Wolff quoted Murdoch as saying Trump was "a f-----g moron."

She also noted that Wolff said CNN had published an unsubstantiated dossier compiled by former British spy Christopher Steele about Trump's alleged dealings with Russians. The dossier, however, was actually published by Buzzfeed.com.

"That's ... one fact check away from getting it right," she said.

According to vox.com, the book claims that Senate Majority Leader Mitch McConnell's staff had rejected a reconciliation meeting in August on grounds that the senator was getting a haircut. At the time, Trump was furious with McConnell over the Senate's failure to repeal and replace Obamacare.

McConnell's deputy chief of staff, Don Stewart, denied the report on Saturday.

I can confirm: this never happened. Neither the author nor vox bothered to check.

In another error, the book says Washington Post reporter Mark Berman was in the Four Season restaurant the morning Ivanka Trump showed up for breakfast. Berman, however, says he wasn't there.

An update for this thread: Wolff acknowledges mixing up Mark Berman (me) and Mike Berman (not me), apologizes for that error in the book

On Twitter, Trump claimed he "authorized Zero access to White House" for Wolff and "never spoke to him for book."

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!

In an interview on NBC's "TODAY" on Friday, Wolff insisted that he had spoken with Trump for the book.

"Whether he realized it was an interview or not, I don't know, but it certainly was not off the record," he said. "My window into Donald Trump is pretty significant."

Wolff also defended the book's accuracy.