The president-elect has previously floated a nationwide mask mandate to combat the coronavirus, which he later acknowledged would be beyond the ability of the president to enforce.

“We could save tens of thousands of lives if everyone would just wear a mask for the next few months. Not Democratic or Republican lives, American lives,” Biden said.

Trump retweeted a post that appeared to make fun of a photo of Biden wearing a mask in public, though he later said he didn’t mean to be critical.