Trump doesn't back down from slamming tell-all, calling author a 'total loser,' the book 'boring'

The president also continued to refer to Steve Bannon as 'Sloppy Steve.'

— -- Donald Trump isn't backing down from attacking journalist Michael Wolff and his scandalous new tell-all "Fire and Fury," unleashing a tweet late Friday night in which he calls the author a "total loser," the book "untruthful" and again referring to Steve Bannon as "Sloppy Steve."

"Michael Wolff is a total loser who made up stories in order to sell this really boring and untruthful book," Trump wrote of the book, which hit bookstores Friday. "He used Sloppy Steve Bannon, who cried when he got fired and begged for his job. Now Sloppy Steve has been dumped like a dog by almost everyone. Too bad!"

Wolff joins a club of "total losers" -- foes of the president who he's described as such -- including Mark Cuban, Cher, Rosie O'Donnell and Seth Meyers.

The tweet included a retweet of an image the GOP tweeted earlier in the day, featuring negative purported reviews of the book, which the GOP refers to as "Liar and Phony," not "Fire and Fury."

Despite the president's claims about the authenticity of the book's content, Wolff said in an interview Friday morning that he "absolutely spoke to the president" and that he stands by his reporting in the book.

“Whether he realized it was an interview or not, I don't know," Wolff said of Trump on the "Today" show. "But it certainly was not off the record.”

The author said he spent three hours with Trump including over the course of the campaign and in the White House after the inauguration.

"My window into Donald Trump is pretty significant," Wolff said.

Trump's newfound disdain for Bannon, who previously served as White House strategist, stems from the fact that Bannon is quoted in the book worrying about the legal implications of the June 2016 meeting between Donald Trump Jr., Jared Kushner, Paul Manafort and a group of Russians who promised damaging information against Hillary Clinton.

"Even if you thought that this was not treasonous, or unpatriotic, or bad [expletive], and I happen to think it’s all of that you should have called the FBI immediately,” Bannon is quoted as saying, according to Wolff's book.

Trump introduced the nickname "Sloppy Steve" in a tweet Thursday night, writing "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!"