Mr. Biden, the former vice president, leads Mr. Trump by five percentage points in Wisconsin and by a wider, nine-point margin in neighboring Minnesota, a Democratic-leaning state that Mr. Trump has been seeking to flip with his vehement denunciations of rioting and crime.

The president has improved his political standing in Wisconsin in particular with an insistent appeal to Republican-leaning white voters alarmed by local unrest. But in both Midwestern states, along with the less-populous battlegrounds of Nevada and New Hampshire, Mr. Trump has not managed to overcome his fundamental political vulnerabilities — above all, his deep unpopularity with women and the widespread view among voters that he has mismanaged the coronavirus pandemic…

Voters in Wisconsin and Minnesota are split on the question of which candidate they trust more to handle the subject of law and order, which Mr. Trump has tried to elevate. But the poll, conducted among likely voters, showed they prefer Mr. Biden by clear margins on the issues of the coronavirus pandemic, race relations and fostering national unity, a sobering result for the president’s supporters.