Chief medical advisor to President Biden Dr. Anthony Fauci told lawmakers that he trusted Chinese scientists at the Wuhan Institute of Virology, saying he did not believe they attempted to modify viruses to make them more contagious.

Fauci assured Senators during a contentious committee hearing that taxpayer funds were not used to support "gain of function" research – the process in which a virus is modified to make it more infectious.

But not all GOP lawmakers were convinced by Fauci’s testimony.

LAWMAKERS CALL FOR FAUCI RESIGNATION OR FIRING 'IMMEDIATELY' AMID COVID FLIP-FLOPS

"How do you know they didn’t lie to you and use the money for gain of function research anyway?" Louisiana Republican Sen. John Kennedy asked Fauci.

The infectious disease specialist explained that the National Institutes of Health (NIH) had seen the results of the experiments conducted using U.S. government funds, adding that the viruses studied could also be found in public databases. 

"None of that was gain of function," he told Kennedy.can you hear me

"How do you know that they didn’t do the research and not put it on their website?" the Louisiana Republican shot back.

"There’s no way of guaranteeing that," Fauci conceded. Adding, "But in our experience with grantees, including Chinese grantees…they’re very competent, trustworthy scientists.

"I’m not talking about anything else in China I’m talking about the scientist," he continued. "You would expect that they would abide by the conditions of the grant -- which they’ve done for the years that we’ve had interactions with them."

"So you don’t think the Chinese would lie to you?" Kennedy questioned.

Fauci told the senator that he could not comment on the Chinese Communist Party’s (CCP) alleged influence over Chinese scientists, but said he knew the scientists that he has worked with to be "trustworthy."

Fauci has faced pushback from Republicans on the Hill calling for his resignation over what they say is a shift in his position on U.S.-funded research with the Wuhan Institute of Virology.

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On Tuesday, the infectious disease specialist told lawmakers the NIH granted the Wuhan Institute of Virology $600,000 over a five-year period through the non-profit EcoHealth Alliance.

The grant helped fund a study of the transmission of coronaviruses from bats to humans, in order to better understand the SARS-CoV-1 epidemic in the early 2000s.

Biden announced Wednesday that he has ordered a deep dive into the origins of the coronavirus pandemic that shut down global economies, killed nearly 3.5 million people, and infected over 168 million worldwide. 

The intelligence review will look into what he said are the two most "likely scenarios" of the virus’ origin.

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Republicans have called for a separate investigation into whether the pandemic was a result of a man-made virus that leaked from the lab – a  theory that has gained traction in recent months among top U.S. officials.