President Trump speaks during a meeting at the White House on Jan. 4. (Andrew Harnik/AP)

President Trump on Thursday night lambasted the author of a new damning book about his administration, calling it “phony” and asserting he never gave its author reporting access to the White House.

“I authorized Zero access to White House (actually turned him down many times) for author of phony book!” Trump wrote in a tweet. “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!”

Trump’s legal team on Thursday threatened possible libel charges against the book’s author, Michael Wolff, its publisher and his former chief strategist, Stephen K. Bannon. Explosive comments attributed to Bannon are featured throughout the book, including a suggestion that a meeting during the campaign between Donald Trump Jr. and a Russian lawyer was “treasonous.”

The book was originally scheduled to release next week, but Wolff and his publisher announced Thursday its publication date would be moved up to Friday because of “unprecedented demand.”

Wolff has said his book was based on 200 interviews with White House and campaign staffers, including Bannon. Some conversations were on the record, while others were off the record or on “deep background,” allowing him to relay a “disembodied description of events provided by an unnamed witness to them.”

The author, a New York writer and media executive, has previously been accused by critics of “pushing the facts as far as they’ll go, and sometimes further than they can tolerate,” as The Washington Post’s Paul Farhi wrote Wednesday.

On Wednesday, White House press secretary Sarah Huckabee Sanders said Trump only had “one brief conversation” with Wolff “that had nothing to do, originally, with the book.” Bannon, she said, was the one signing off on “close to 95 percent” of the author’s dialogue with White House staff. She estimated the author had “roughly just over a dozen interactions with officials at the White House.”

Former White House press secretary Sean Spicer also spoke of Wolff’s White House access in an interview with conservative commentator S.E. Cupp on CNN Thursday.

“I talked to him,” Spicer said. “He came in and said ‘I’d like to write a book about the president.’”

Bannon set up appointments for the author to “come in and visit him over time,” Spicer said. But, Spicer added, “we don’t know how much access he got.”

In a piece published Thursday in the Hollywood Reporter, Wolff provided his own account of how he gained reporting access to the White House. After the election, Wolff said, he spoke to Trump about his desire to write a book, and proposed that he report from inside the White House as a “fly on the wall.”

“A book?” Trump responded, according to Wolff. The author claimed that Trump seemed to say “sure, knock yourself out.”

Wolff then managed to meander his way into the White House and into the proximity of its cast of characters, he described in the Hollywood Reporter:

“Since the new White House was often uncertain about what the president meant or did not mean in any given utterance, his non-disapproval became a kind of passport for me to hang around — checking in each week at the Hay-Adams hotel, making appointments with various senior staffers who put my name in the ‘system,’ and then wandering across the street to the White House and plunking myself down, day after day, on a West Wing couch.

“The West Wing is configured in such a way that the anteroom is quite a thoroughfare — everybody passes by. 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.”

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