(NewsNation) — Lawyers for President Joe Biden’s son Hunter say they plan to sue Fox News “imminently,” according to a letter obtained by NewsNation.

“For the last five years, Fox News has relentlessly attacked Hunter Biden and made him a caricature in order to boost ratings and for its financial gain,” his attorney, Mark Geragos, said in a statement. “The recent indictment of FBI informant (Alexander) Smirnov has exposed the conspiracy of disinformation that has been fueled by Fox, enabled by their paid agents and monetized by the Fox enterprise. We plan on holding them accountable.”

Prosecutors say Smirnov, 43, falsely told his FBI handler that executives from the Ukrainian energy company Burisma paid the president and Hunter Biden about $5 million each around 2015. Smirnov has pleaded not guilty to charges against him. Charging documents say Smirnov provided “false and derogatory information” to federal agents about both Bidens in 2020.

Smirnov’s claims are the main focus of a GOP-led House impeachment inquiry into Joe Biden that has remained stalled. Last month, Republican Rep. James Comer, chairman of the House Oversight and Accountability Committee, announced that he wants to seek testimony from President Biden himself, accusing him of being either “complicit or incompetent” in Hunter Biden’s business dealings.

White House officials have previously demanded Fox News retract its coverage of bribery allegations, saying they are “false,” NewsNation partner The Hill reported. In a letter to Fox News obtained by The Hill in March, White House special assistant to the president Ian Sams said that citing the number of times Jesse Watters and Sean Hannity promoted Smirnov’s accusations would take “multiple pages.”

“As you of course now know, the source of this allegation has been federally indicted for making the whole thing up,” Sams wrote. “Despite this, Fox has taken no steps to retract, correct, or update its reporting on this false allegation from 2023.”

Fox, in a statement to NewsNation, defended what it called its “constitutionally protected coverage” of Hunter Biden.

“Mr. Biden is a public figure who has been the subject of investigations by both the Department of Justice and Congress, has been indicted by two different US Attorney’s Offices in California and Delaware, and has admitted to multiple incidents of wrongdoing,” a spokesperson said in an email. “Consistent with the First Amendment, Fox News has accurately covered these highly publicized events as well as the subsequent indictment of an FBI informant who was the source of certain claims made about Mr. Biden.”

After analyzing transcripts in the Kinetiq video database for all original programming on Fox News Channel, Media Matters, a left-leaning journalism watchdog group, determined the outlet had mentioned Hunter Biden at least 13,440 times since Jan. 3, 2023. Media Matters also said Comer had appeared on Fox weekday programs at least 137 times since the start of this congressional term.

However, Fox’s references to Hunter Biden have fallen every month in 2024, going from 786 in January to only 60 as of late April.

Fox News has seen other legal challenges in recent years. In April 2023, the channel reached a settlement with Dominion Voting Systems. Dominion, in a defamation lawsuit, stated Fox News and its parent company bulldozed the voting company’s business and subjected employees to threats by falsely implicating it in a bogus conspiracy to rig the 2020 election against former President Donald Trump. Fox responded by saying it reported on Trump’s challenges to the election results. Still, the news channel agreed to pay Dominion $787.5 million.

Another company that produces voting machines, Smartmatic, also sued Fox over false claims made by the network’s hosts. A judge in January tossed out Fox News’ claims that Smartmatic is trying to suppress its free speech, meaning the suit will continue to an eventual trial.

Hunter Biden, meanwhile, has been charged with nine felony and misdemeanor tax offenses filed in Los Angeles and has pleaded not guilty to them. Attorney Abbe Lowell said the indictment against Hunter Biden, which accuses him of scheming to avoid paying $1.4 million in taxes while living an extravagant lifestyle, was politically motivated. U.S. District Judge Mark Scarsi, however, ruled in April of this year that there is little support for these claims.

“Defendant fails to present a reasonable inference, let alone clear evidence, of discriminatory effect and discriminatory purpose,” he wrote.

Hunter Biden’s legal team maintained that the handling of the case was abnormal.

“We strongly disagree with the court’s decision and will continue to vigorously pursue Mr. Biden’s challenges,” Lowell said in a statement.

NewsNation digital producer Steph Whiteside and The Associated Press contributed to this report.