The U.S. government’s top infectious disease expert, Dr. Anthony Fauci, on Tuesday angrily accused a senator of making false accusations that led to threats against him — all to raise political money.

Sen. Rand Paul, Republican of Kentucky, has repeatedly said Fauci lied about the pandemic, claiming during a hearing on Tuesday that he was trying to “override” some scientists who disagreed with him.

Paul and other conservative critics have focused their anger on how the pandemic is being handled, while Fauci is the director of infectious diseases at the National Institutes of Health and chief medical adviser to President Joe Biden. Due to threats and harassment against him and his family, Fauci has required increased security measures since 2020.

On Tuesday, Fauci expressed disappointment that the senator has still “blamed me for things that are totally untrue” and “ignited the lunatic out there” after the pandemic has gotten so far.

He pointed to the arrest last month of a California man for speeding in Iowa and told a sheriff’s deputy that he was on his way to the nation’s capital to kill a list of those in power, including Fauci. Court documents show the man, Kuacha Brillion Xiong, of Sacramento, had an AR-15-style rifle, ammunition and body armor in the car.

Fauci said Paul’s website has a “Fire Dr. Fauci” page that includes calls for political donations ranging from $5 to $100.

He accused Paul of using the pandemic “for your political gain”.

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The spat overshadowed a hearing by the Senate Health, Education, Labor and Pensions Committee, which was set to examine whether policy changes are needed as the U.S. battles the highly contagious variant of the omicron.

One of the main complaints from Republicans and Democrats is the continued lack of testing to make it easier for people to tell if they have COVID-19 so they can stay home instead of spreading it.

“I’m just saying to all of you right now that the test is broken,” said the committee’s ranking member, Sen. Richard Burr, Republican of North Carolina, angrily.

Still, Burr and several other lawmakers on both sides of the aisle thanked Fauci for his work in fighting the pandemic.

But later in Tuesday’s hearing, Fauci was furious when Sen. Roger Marshall of Kansas accused him of concealing financial disclosure forms requested by public officials.

“It’s unusual that you’re being misled,” Fauci responded, and the documents are publicly available on request. At the end of the exchange, Fauci can be heard muttering off-camera, “What an idiot.”