EXCLUSIVE: Republican Sens. Marsha Blackburn, Marco Rubio and Tom Cotton are calling on Dr. Anthony Fauci to resign, saying he has "lost the confidence of the American people" amid controversy surrounding the origins of COVID-19 —and if he won’t step down, the Republican senators are urging President Biden to fire him. 

"Fauci needs to step down," Blackburn told Fox News in an interview this week. "And the Biden Administration should ask him to step away from his post." 

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"For 16 months we have seen Dr. Fauci withhold information, dismiss plausible explanations of COVID’s origin, and outright lie to Congress," Rubio told Fox News. "He is supposed to be a fact-based public health official, not a pundit distorting the truth to conform with his personal judgment." 

Rubio added: "If President Biden is committed to science and finding the truth about COVID, he needs to fire Fauci."

"Dr. Fauci has lost the confidence of the American people with his repeated evasions, misdirection, and politicized statements," Cotton said. "If he won’t resign, Joe Biden should fire him." 

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The Republican calls for Fauci to step down from his post come after Fauci’s emails were released through a Freedom of Information Act filing last week, which revealed his evolving recommendations on masks, and his early doubts of the theory that COVID-19 leaked from a lab.

Fauci, on Wednesday, responded to criticisms, saying that the attacks on him "are attacks on science." 

"All of the things that I have spoken about consistently from the very beginning have been fundamentally based on science," Fauci said during an interview with MSNBC’s Chuck Todd. "Sometimes those things were inconvenient truths for people and there was pushback against me, so if you are trying to, you know, get at me as a public health official and a scientist, you’re really attacking not only Dr. Anthony Fauci, you’re attacking science." 

He added: "And anybody that looks at what is going on clearly sees that. You have to be asleep not to see that. That is what is going on. Science and the truth are being attacked." 

The White House is defending Fauci amid criticism, calling him an "undeniable asset" to the country during the pandemic, with President Biden saying he is "very confident" in Fauci. 

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This week, White House Coronavirus Task Force Director Jeffrey Zients defended Fauci against attacks, crediting him with helping to "invent and invest" in the mRNA of vaccine platform "over the last two decades so that we would be ready in case the worse should happen." 

"That’s how you got your vaccine in the first place," Zients said. "So, thank you, Dr. Fauci." 

And last week, after his emails were released, White House press secretary Jen Psaki said Fauci has "been an undeniable asset in our country’s pandemic response," and said there was no circumstance where she could imagine President Biden firing Fauci. 

"He’s overseen management of multiple global health crises, and attacks launched on him are certainly something we wouldn't stand by," Psaki said, adding that she wouldn’t have more to add on the matter. 

"Can you imagine any circumstance where President Biden would ever fire him?" Fox News’ Peter Doocy asked. 

"No," Psaki replied.

In one email National Institutes of Health (NIH) Director Francis Collins sent Fauci, director of the National Institute of Allergy and Infectious Diseases (NIAID), a link to a Fox News report that gave credence to the theory coronavirus could have originated in the Wuhan Institute of Virology with the subject line "conspiracy gains momentum." Fauci's response is entirely redacted. 

In a February 1, 2020 email, immunologist Kristian Andersen wrote to Fauci arguing the virus had "unusual features" that could suggest lab manipulation. Andersen and his team then looked into the theory further and their studies showed the virus was not a "laboratory construct or a purposefully manipulated virus," according to the emails. 

Another email came to Fauci from Peter Daszak, who runs EcoHealth Alliance, which received millions in grants from the NIH, including a $600,000 grant from Fauci's agency, the NIAID, that it later paid to the Wuhan Institute of Virology to study the risk that bat coronaviruses could infect humans.

"I just wanted to say a personal thank you on behalf of our staff and collaborators, for publicly standing up and stating that the scientific evidence supports a natural origin for COVID-19 from a bat-to-human spillover, not a lab release from the Wuhan Institute of Virology," Daszak said in an email. Fauci replied: "Many thanks for your kind note." 

President Biden last month released a public statement revealing that the U.S. intelligence community has "coalesced around two likely scenarios" for the origins of COVID-19, "including whether it emerged from human contact with an infected animal or from a laboratory accident," and asked for "additional follow-up." 

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The president asked the intelligence community to "redouble their efforts to collect and analyze information that could bring us closer to a definitive conclusion, and to report back to me in 90 days," Biden said.

A source familiar told Fox News that the administration is not ruling out scientifically credible hypotheses but is focusing its attention on the scenarios mentioned in the president’s statement Wednesday. 

The source was not aware of current evidence supporting an intentional lab leak and instead stressed the "laboratory accident" verbiage in Biden’s statement. 

Fauci has since said he is "keeping an open mind" about the virus' origins. 

Meanwhile, Blackburn, Rubio and Cotton are not alone. House Republican Leader Kevin McCarthy has also called for Fauci to step down or for Biden to fire him from his post. 

And a number of other House Republicans are demanding Fauci testify before Congress on his emails, U.S.-funded research at the Wuhan Institute of Virology, and more. 

Fox News' Morgan Phillips and David Rutz contributed to this report.