University of Wisconsin-Madison: “The Elections Research Center conducted surveys in Michigan, Pennsylvania, and Wisconsin between July 27 and August 6, 2020. The surveys asked voting-age citizens who they plan to vote for in the general election.”
“Among other items, the survey also asked respondents about their reasons for supporting the candidates and opinions about President Trump’s handling of the coronavirus pandemic and protests over policing. The surveys reveal that Vice President Joe Biden has a solid lead over President Trump across all three battleground states. Biden’s advantage is largely the result of consolidating the Democratic vote and attracting support from voters who supported minor party candidates or did not vote in 2016. Since February, previously undecided voters have shifted in Biden’s direction, and views surrounding Trump’s handling of both the coronavirus and protests over policing are closely tied to vote choice.”