President Donald Trump threatened his former chief strategist Steve Bannon with legal action over "defamatory" statements about Trump's son and son-in-law over a meeting with Russians during the 2016 U.S. presidential campaign.
It already has cost him a key backer.
Although President Trump has been adamant about stopping leaks to the media, aides said that wasn't the intent of the action on cellphones.
Mr Bannon's reaction to the book controversy has been muted.
Trump hailed that move on Twitter Friday, saying: "The Mercer Family recently dumped the leaker known as Sloppy Steve Bannon".
Some of the harshest commentary in the book allegedly came from former chief strategist Mr Bannon, who is quoted as describing a Trump Tower meeting between Donald Trump Jr, Jared Kushner, campaign chairman Paul Manafort and Russian lawyer Natalia Veselnitskaya as "treasonous" and "unpatriotic".
A parade of administration officials and allies worked to discredit Bannon as a disgruntled has-been.
The release left Trump "furious" and "disgusted", said White House Press Secretary Sarah Huckabee Sanders, who complained that the book contained "outrageous" and "completely false claims against the president, his administration and his family".
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"I'm not aware that they were ever particularly close", Sanders said Thursday.
Still, Trump insisted Thursday that he doesn't talk to Bannon, calling it a "misnomer".
Wolff's book - which he says is based on interviews with Trump, his senior aides and others - also mentions that Trump eats food from McDonald's because he believes it to be safe from poison, and that his team did not believe he was capable of winning the election. It's unclear how Bannon's new rift with the president, and the related impact on major donors, will affect the organization, dubbed Citizens of the American Republic. "I've never had such conversation in the White House, outside of the White House, with Jared Kushner, with anybody else", Mr Blair said. Bannon believes that they have exposed Trump to the Russian Federation probe that could topple his presidency and that Trump would be able to accomplish more without them.
Some Trump allies also expressed satisfaction that Bannon appeared to be finally cast out of the president's inner circle.
"When he was sacked, he not only lost his job, he lost his mind", Trump said in a statement, adding, "Steve pretends to be at war with the media, which he calls the opposition party, yet he spent his time at the White House leaking false information to the media to make himself seem far more important than he was".
Republican Senate Majority Leader Mitch McConnell, a longtime punching bag for Bannon, reveled in the aide's break with the president.
"Steve Bannon has nothing to do with me or my presidency".
Bannon did not respond to ABC News' request for comment Wednesday.