President Trump on Friday informed CNN President Jeff Zucker and the news network that he intends to sue them over biased reporting and seek substantial financial damages.

In a letter to Mr. Zucker and other CNN executives, Mr. Trump’s personal lawyer detailed evidence of Mr. Zucker’s “vendetta” against the president and evidence of a CNN campaign to “take down President Trump” with biased reporting on the impeachment effort, as documented in an undercover video by Project Veritas.

“Never in the history of this country has a president been the subject of such a sustained barrage of unfair, unfounded, unethical and unlawful attacks by so-called ‘mainstream’ news, as the current situation,” Trump lawyer Charles Harder said in the letter, a copy of which was obtained by The Washington Times.

CNN scoffed at the lawsuit threat.

“This is nothing more than a desperate PR stunt and doesn’t merit a response,” CNN Vice President of Communications Matt Dornic said in an email to The Times.

A lawsuit over bias against a news outlet poses significant challenges for Mr. Trump, including running up against First Amendment rights.

Mr. Harder said the Project Veritas video was “the tip of the iceberg of the evidence my clients have accumulated over the recent years.”

He said the biased reporting violated the Lanham Act, a copyright protection law, suggesting that the news network does not live up to its claims of journalistic integrity.

“Accordingly, my clients intend to file legal action against you, to seek compensatory damages, treble damages, punitive damages, injunctive relief, reimbursement of legal costs, and all other available legal and equitable remedies, to the maximum extent permitted by law,” Mr. Harder wrote.

He noted that the CNN website describes the network as “journalists” and truth seekers,” and that the network’s motto is “The Most Trusted Name in News.”

“Recently released video footage of individuals alleged to be your employees (https://www.youtube.com/watch?v=m7XZmugtLv4) indicates that your

reporting relating to President Trump is contrary to your own mission and the [Society of Professional Journalists’] Code of Ethics,” Mr. Harder wrote.

The letter detailed evidence of bias revealed in the undercover video.

CNN employees are caught saying that CNN is focused on trying to “take down President Trump” and driven by a “personal vendetta” that Mr. Zucker purportedly has against the president, rather than objectively reporting the news.

Nick Neville, media coordinator at CNN, says in the video that “Jeff Zucker, basically the president of CNN, has a personal vendetta against Trump” and “an ongoing feud with Trump since The Apprentice,” the hit reality TV show starring Mr. Trump on which Mr. Zucker was a producer.

Mr. Neville also says in the video that he wants to report “the truth” and do “dogged reporting. But then you have higher up executives like Zucker and other people, who are saying we gotta make profits … so it turns into like certain things that you do are trying just to attract viewers, then it becomes kind of a comedy show.”

Cary Poarch, a CNN employee in the Washington bureau, says in the video: “CNN purports to be facts first, and that’s just not the case.”

In another clip, CNN Media Coordinator Christian Sierra says Mr. Zucker wants “impeachment every single day to be the top story [and] he wants impeachment above all else.”

“I hate how everything is all Trump all the time now. Everyone at the network complains about it. They hate covering Trump every day,” Ms. Sierra says. “Our Democratic interviews are like softballs, compared to the Republicans.”