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Dr. Anthony Fauci was caught on a hot mic calling a Republican senator a "moron" during a contentious Capitol Hill hearing on Tuesday. 

"What a moron, Jesus Christ!" Fauci could be heard saying after being questioned by Republican Sen. Roger Marshall of Kansas about disclosing his investments to Congress, which Fauci, the highest-paid federal employee in government, says he has done for decades. 

Dr. Anthony Fauci

Dr. Anthony Fauci, White House chief medical adviser and director of the NIAID, participates in the White House COVID-19 Response Team's regular call with the National Governors Association in the South Court Auditorium in the Eisenhower Executive Office Building on the White House Campus, Monday, Dec. 27, 2021, in Washington. (AP Photo/Carolyn Kaster) 

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"As the highest-paid employee in the entire federal government," Marshall, a military veteran and a physician, asked. "Yes or no, would you be willing to submit to Congress and the public a financial disclosure that includes your past and current investments?"

Fauci responded, "I don't understand why you're asking me that question. My financial disclosure is public knowledge and has been so for the last 37 years or so, 35 years."

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Marshall then accused "big tech giants" of keeping that information from the public, to which Fauci said, "All you have to do is ask for it. You're so misinformed. It's extraordinary."

Dr. Anthony Fauci

Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases and chief medical adviser to the president, listens during a meeting with the White House COVID-19 Response Team on the latest developments related to the Omicron variant in the South Court Auditorium in the Eisenhower Executive Office Building on the White House Campus in Washington, Tuesday, Jan. 4, 2022.  ((AP Photo/Andrew Harnik))

The two continued to spar before Democratic Sen. Patty Murray of Washington intervened, at which point Fauci was caught on the hot mic disparaging Marshall.

Fauci's office did not immediately respond to a request for comment from Fox News.

In a statement released after the hearing, Marshall said that "contrary to what Dr. Fauci said, Dr. Fauci’s financial disclosures for the years of the COVID pandemic are not public."

"I understand that Anthony Fauci had a very frustrating day: having a bombshell report show he in fact did award U.S. tax dollars for gain-of-function research at the Wuhan Institute of Virology and being called out about his personal financial disclosure during the COVID pandemic NOT being publically available must be very frustrating," the statement said. "Calling me a moron during a Senate hearing may have alleviated the stress of the least trusted bureaucrat in America, but it didn’t take away from the facts."

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In the Senate hearing, Fauci also clashed with Republican Sen. Rand Paul, accusing him of "distorting everything about me," which he said is Paul's "usual fashion."

Dr. Anthony Fauci and Sen. Rand Paul

Dr. Anthony Fauci, White House chief medical adviser and director of the NIAID, gives and opening statement during a Senate Health, Education, Labor, and Pensions Committee hearing. At right, Sen. Rand Paul. (GREG NASH/POOL/AFP via Getty Images  |   Photographer: Greg Nash/The Hill/Bloomberg via Getty Images)

Paul, a fierce critic of the National Institute of Allergy and Infections Diseases director, accused Fauci of playing a role in smearing doctors from Harvard, Oxford and Stanford who had positions different from his own.

Fox News' Ronn Blitzer contributed to this report