In Wisconsin, the Democratic governor, Tony Evers, had sought to have in-person voting delayed, but the Republican-controlled State Legislature and the conservative-led Wisconsin Supreme Court insisted on going ahead with it. And in a 5-4 ruling along ideological lines, the federal Supreme Court shot down Democratic efforts to extend the absentee voting deadline — despite concerns about public health and reports that many voters had not received their requested mail ballots.

Republicans have long sought to enact voting restrictions that disproportionately affect racial minorities, poor people and younger voters, pointing to the threat of voter fraud despite the fact that it is very rare. And both parties have long acknowledged that making voting easier helps Democrats.

But the coronavirus has turbocharged this debate, with Democrats and some state Republicans encouraging vote-by-mail measures to make it safer to cast ballots.

Congressional Democrats now say they are committed to inserting voting-access provisions into a coronavirus relief bill. Such a national law could help to prevent Republican officials in key swing states like Wisconsin from restricting access to things like vote-by-mail.

Another proposed regulation would force states to allow at least 20 days for early, in-person voting.