President Donald Trump has threatened to go to the courts to block the publication of a new book about his White House, but any potential litigation may already be doomed.

Lawyer Charles Harder of Harder Mirell & Abrams sent a “cease and desist” letter to author Michael Wolff and his publisher, Henry Holt Co., Thursday, according to media reports. The letter demanded that the company refrain from publishing Wolff's book, “Fire and Fury,” or face legal action. The publisher said it pushed the release date from Tuesday, Jan. 9, to Friday due to the book's demand.

Harder sent a similar letter Wednesday to Steve Bannon, accusing the former Trump adviser, who's quoted in the book, of defamation and violating his employment contract. In a statement, Harder said legal action was “imminent.”

But several First Amendment lawyers doubt any lawsuits to block the publication of the book, or against Bannon, can go far.

“To call it an empty threat is a significant understatement,” said Theodore Boutrous, a Los Angeles-based partner at Gibson, Dunn & Crutcher and media law expert. “No court in the world would halt that book.”

Excerpts from the book released Wednesday quote Bannon and other top aides as criticizing the president and his family. In a statement, Trump said Bannon had “very little” to do with his 2016 victory.

“When he was fired, he not only lost his job, he lost his mind,” the president said of his former adviser.

Harder did not reply to a request for comment. The Beverly Hills lawyer, who successfully represented Hulk Hogan in his libel suit against Gawker, is known for sending threatening letters and launching high-profile defamation lawsuits. He also sent a letter to New York magazine on behalf of the late Roger Ailes in 2016, though a suit was never filed. Harder also represented Melania Trump in a lawsuit against the Daily Mail, which was settled last year.

Boutrous, who is also involved in the DACA litigation against the administration, said that asking a court to block publication of a book is a request for a prior restraint, which the U.S. Supreme Court has held as unconstitutional except in very narrow circumstances, such as when publishing the information would threaten lives.

The released excerpts from the book, Boutrous said, appear to show personal and political opinions of Wolff and Bannon and others quoted, which fit into categories protected by the First Amendment.

“I think they're going to get laughed out of court if they ask for a prior restraint against the book,” said Charles Tobin, a partner at Ballard Spahr and co-practice leader of the firm's media and entertainment law group. Tobin has represented media companies such as CNN against the Trump administration.

Tobin said, based on the excerpts of the book he had seen, the same would go for a defamation suit against Bannon.

Trump is no stranger to libel and defamation suits, often threatening them in his past life as a private citizen, though he rarely followed through. Recently, however, he's been a defendant in such a case. Last month, a judge heard oral arguments in a case where Summer Zervos argued Trump's public statements that she lied in alleging he groped her amounted to defamation.

The case is still pending, but Trump's lawyers claimed the court could not even hear the case because as president, Trump is immune to civil defamation suits.

If Trump initiates his own defamation lawsuit, the logic in the Zervos case won't hold up, Tobin said.

“He can't claim executive privilege as a defendant and then be free to prosecute his own claim,” Tobin said. “Donald Trump has had a love-hate relationship with the First Amendment.”

Another potential pitfall for Trump in bringing such a case would be the opportunity for the defendants to pursue discovery and take depositions. Still, Tobin doubted such a case would make it past a preliminary motion to dismiss.

Even if Harder never files the lawsuits, Boutrous said the attempt to dissuade Wolff or Henry Holt from publishing the book by sending the letters is undermined by the faulty legal theory they outline.

“It really makes no sense,” Boutrous said. “Even the tactic of trying to chill speech by threatening these lawsuits seems here destined to fail, because the notion of these sorts of lawsuits is so unrealistic in terms of their success. So it's really bizarre strategy.”