(CNN) Dr. Anthony Fauci has been reluctant to support a federal mask mandate.
"A national mandate probably would not work," he said on Sept 15 during a news conference with Vermont Gov. Phil Scott.
Fauci, the director of the National Institute of Allergy and Infectious Diseases, has been urging Americans to use masks for months. "I have trust in the American people that if we put a strong emphasis on the importance of wearing masks, that we will come around and do that and get that percentage up above the relatively low percentage of people that are using masks," Fauci said on July 21 on NPR's Morning Edition.
But he has said before that he doesn't think a federal law would be the way to go.
"I don't like to be authoritarian from the federal government, but at the local level, if governors and others essentially mandate the use of masks when you have an outbreak, I think that would be very important," Fauci told Alabama Sen. Doug Jones during a Facebook live event in July.
"Well, if people are not wearing masks, then maybe we should be mandating it," Fauci told CNN's Erin Burnett Friday.
Covid-19 has been worsening across the United States, with cases rising in 32 states Friday and holding steady in 17 more. The University of Washington's Institute for Health Metrics and Evaluation said the country was entering a winter surge as new infections passed 75,000 in a single day on Friday and more than 800 deaths were reported.
Mask mandates may be tricky to enforce, but it might be time to call for them, Fauci said.
"There's going to be a difficulty enforcing it, but if everyone agrees that this is something that's important and they mandate it and everybody pulls together and says, you know, we're going to mandate it but let's just do it, I think that would be a great idea to have everybody do it uniformly," he said.
As cooler weather comes, people need to "double down" on measures that work, Fauci said. "Universal mask wearing" is one, he said, as is keeping a distance from others and frequent hand washing. "They sound very simple. But we're not uniformly doing that and that's one of the reasons we're seeing these surges," Fauci said.