President Donald Trump said Sunday the U.S. had stockpiled 29 million pills of an anti-malaria drug he’s repeatedly pushed as a potential treatment for COVID-19, despite persistent warnings from the nation’s top infectious disease expert there is no “strong” evidence yet the medication could help rein in the ongoing pandemic.

“What do you have to lose?” Trump asked several times during a briefing at the White House, later saying: “I want them to try it, and it may work and it may not work. But if it doesn’t work, there is nothing lost by doing it. What I want is to save lives, but I don’t want it to be in a lab for a year and a half.”

He added: “I’m not acting as a doctor, I’m saying do what you want, but there are some good signs.”

The comments add to Trump’s growing persistence that hydroxychloroquine, an FDA-approved malaria prevention drug, could help save American lives as infection rates in the country topped 337,000. More than 9,600 people have died.

But the president’s hopeful claims about the drug go against the advice of many doctors, including Dr. Anthony Fauci, who leads the National Institute of Allergy and Infectious Diseases. Fauci has repeatedly and aggressively thrown water on the idea in recent days. He told CBS on Sunday we can’t “definitively say it works,” calling data thus far merely “suggestive.” In an interview with Fox News a day before, he said the country had to be “careful that we don’t make that majestic leap to assume that this is a knockout drug.” And during the press conference on Sunday, he said the country’s best hope right now to rein in the spread of the virus was simply “mitigation, mitigation, mitigation,” referring to social distancing measures and frequent hand-washing.

When a reporter attempted to ask Fauci about the president’s claims on Sunday, Trump refused to let him answer, saying the doctor had already done so “15 times.”