The survey, which was conducted June 24 and 25, before Biden made his position known, found that a full 65 percent of Americans now agree that masking up in public should be mandatory. That’s 10 percentage points higher than the number of Americans (55 percent) who said in a May 22 Yahoo News/YouGov poll that the government should require “social distancing measures such as wearing masks in stores.”

Yet support for mandatory mask measures — which one study estimates have already prevented as many as 450,000 COVID-19 cases in the states that have enacted them — breaks sharply along partisan lines. While 86 percent of Democrats and 65 percent of independents back the idea, most Republicans (54 percent) oppose it. Among those who intend to vote for Trump in November, the number who say masks should not be mandatory is even higher: 63 percent.