In a bombshell report Sunday morning, Fox News reported that two frequent guests on the right-leaning cable news channel were “working off the books” to help former New York City mayor and current presidential attorney Rudy Giuliani dig up dirt on President Donald Trump’s leading Democratic opponent—and that the only person who knew about their involvement was the president himself.

Fox News Sunday anchor Chris Wallace broke the news that Giuliani wasn’t acting alone when it came to digging up Ukrainian dirt on Trump’s potential 2020 presidential opponent Joe Biden.

“Two high-profile Washington lawyers, Joe diGenova, who’s been a fierce critic of the Democratic investigation, and his wife Victoria Toensing were working with Giuliani to get oppo research on Biden,” Wallace said at the top of his broadcast.

“According to a top U.S. official, all three were working off the books apart from the administration,” Wallace added. “The only person in government who knows what they were doing is President Trump.”

Giuliani has denied working with any other attorneys in his quest for Ukrainian-provided information on the Biden family in recent appearances on Fox News, denials that the network’s own reporting now call into question.

“No,” Giuliani told Fox News’ Maria Bartiromo on Sunday Morning Futures, when asked if he had worked with other attorneys. “I didn’t work with anybody to try and get dirt on Joe Biden.”

Requests for comment in response to Wallace’s report from diGenova & Toensing, LLP, their eponymous D.C.-based law firm, were not immediately returned. Requests to Giuliani and the White House have also not been returned.

Both diGenova and Toensing have been frequent guests on Fox’s opinion shows, specifically Hannity and Lou Dobbs Tonight. This week, during an appearance on Tucker Carlson Tonight, diGenova blasted Fox News senior judicial analyst Judge Andrew Napolitano as “a fool” for assessing that Trump had committed a crime during his July 25 call with the Ukrainian president.

The remarks sparked a multi-day, on-air scuffle between Fox News anchor Shepard Smith and Fox News host Tucker Carlson. Wallace also appeared to join in the internecine fighting over the network’s coverage of the growing scandal, implicitly criticizing the on-air commentary of some of his Fox News colleagues in recent days.

Both Toensing and diGenova have been two of the president’s fiercest defenders for years. Along with being frequent guests on Fox opinion shows and other conservative media outlets, the husband-wife team has had a close relationship with the president for a while.

In March 2018, they were briefly tapped to join Trump’s special counsel legal team. Days later, however, the president decided against hiring the pair.

“The president is disappointed that conflicts prevent Joe diGenova and Victoria Toensing from joining the president’s special counsel legal team,” Trump attorney Jay Sekulow said at the time. “However, those conflicts do not prevent them from assisting the president in other legal matters. The president looks forward to working with them.”

Revelations this week that Giuliani had been tasked by Trump to coordinate with Attorney General William Barr and Ukrainian President Volodymyr Zelensky in investigating unproven allegations of corruption involving Biden, his son Hunter, and a Ukrainian energy company have pushed long-simmering Democratic support for an impeachment inquiry against the president to a rolling boil.

“I will have Mr. Giuliani give you a call, and I am also going to have Attorney General Barr call and we will get to the bottom of it,” Trump told Zelensky on a July 25 phone call, according to a rough transcript of the conversation released by the White House this week.

Trump and Giuliani have, without providing evidence, accused the former vice president and frontrunner for the Democratic presidential nomination of supporting the removal of a Ukrainian prosecutor to protect Burisma, an energy company advised by his youngest son, Hunter.

“A lot of people want to find out about that so whatever you can do with the attorney general would be great,” Trump said on the call with Zelensky, after asking the newly elected president of Ukraine for a “favor.”

“Biden went around bragging that he stopped the prosecution, so if you can look into it... It sounds horrible to me.”

This story is developing.