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President Donald Trump's top trade adviser, Peter Navarro, said Monday that Dr. Anthony Fauci's caution about the effectiveness of an anti-malaria drug that the president has been urging as a treatment for the coronavirus warrants a "second opinion."

Asked about an Axios report that he and Fauci got into a heated argument about the drug during a coronavirus task force meeting Saturday, Navarro told CNN, "There was that discussion on Saturday, and if we didn't have disagreement and debate in the Trump administration, this administration would not be as strong as it is."

A source told Axios that the dispute started when Navarro said the studies he'd seen on the effects of the drug, hydroxychloroquine, show "clear therapeutic efficacy." Fauci, the director of the National Institute of Allergy and Infectious Diseases, told Navarro there's only anecdotal evidence, leading Navarro to angrily declare that the studies he'd seen are "science, not anecdote."

Three sources familiar with the meeting confirmed to NBC News that the pair had a testy exchange.

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One source said that Navarro was "a little hot" during the exchange and that officials found it "jarring" that he became so animated in front of the vice president and Cabinet secretaries.

Fauci sounded a similar note of caution on the drug in an interview with CBS on Sunday, saying there'd been some reports of the drug's helping — and other reports of it's having zero effect.

Asked to comment on Fauci's statement, Navarro told CNN, "I'll let him speak for himself," but "I have two words for you — second opinion."

Navarro, an economist, was then asked for his qualifications to give medical opinions.

"Doctors disagree about things all the time. My qualifications in terms of looking at the science is that I'm a social scientist. I have a Ph.D. And I understand how to read statistical studies, whether it's in medicine, the law, economics or whatever," Navarro said.

Asked whether he wanted a doctor making trade deals, Navarro said, "touché," before accusing anchor John Berman of engaging in a "false narrative."

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Trump has touted the drug as a potential "game changer" on an almost-daily basis. When Fauci was asked about the drug at the White House briefing Sunday, Trump stepped in and said, "I've answered that question — maybe 15 times."

"You don't have to answer," he told Fauci.

"There's signs it works on this — very strong signs," Trump said. "I've seen things that I sort of like. What do I know? I'm not a doctor. I'm not a doctor, but I have common sense."