Former Vice President Joe Biden and Senator Kamala Harris are calling for a three-month nationwide mask mandate to limit the spread of coronavirus.
During a briefing by public health experts in Wilmington, Biden, the presumptive Democratic presidential nominee, told reporters that all the nation's governors should require this.
"Every single American should be wearing a mask when they're outside for the next three months, at a minimum. Every governor should mandate mandatory mask-wearing," Biden said, suggesting that widespread mask use could save 40,000 lives over the next three months. "Let's institute a mask mandate nationwide starting immediately, and we will save lives."
One July study found that 40,000 lives would have been saved in two months if a national mask mandate for employees had gone into effect for the months of April and May.
Harris, who was chosen this week by Biden to be his running mate and attended the health briefing with him, echoed Biden's call for the mandate.
"That's what real leadership looks like," Harris said. "We just witnessed real leadership, which is Joe Biden said, that as a nation, we should all be wearing a mask for the next three months because it will save lives."
Thirty-four states currently require people to wear facial coverings in public.
Coronavirus face masks: America reacts and rebels
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President Trump ridiculed the idea during a news conference later Thursday.
"While Joe Biden would allow rioters and looters and criminals and millions of illegal aliens to roam free in our country, he wants the federal government to issue a sweeping new mandate to law-abiding citizens," Mr. Trump said. "He wants the president of the United States, with the mere stroke of a pen, to order over 300 million American citizens to wear a mask for a minimum of three straight months, because...he thinks it's good politics, I guess, no matter where they live, and no matter their surroundings."
Mr. Trump has been seen wearing a mask infrequently and only recently pivoted to supporting the wide use of masks in public. In May, Mr. Trump mocked Biden on Twitter for wearing a mask.
According to data from Johns Hopkins University, there are over 5 million confirmed coronavirus cases in the U.S., and over 166,000 Americans have died of the virus.