Unlike in 2012, self-identified Republicans now outnumber Democrats in Times/Siena polls of Wisconsin, Michigan and even Pennsylvania, where the Democratic registration advantage remains significant but has dwindled in recent months.
Instead, Mr. Biden leads with an overwhelming advantage among independent voters, who back him by 20 percentage points in both states.
And though Mr. Biden’s gains among white voters are broad, spanning both those with and without a college degree, he fares far better than Mr. Obama did among white college graduates, while faring worse among those without a four-year degree. As a result, Mr. Biden still trails narrowly in the precincts that flipped from Mr. Obama to Mr. Trump, while holding an overwhelming advantage in the smaller number of predominantly suburban precincts that backed Mitt Romney in 2012 and then supported Mrs. Clinton in 2016.
In Michigan, Senator Gary Peters, a Democrat, faces a surprisingly strong challenge from John James, a graduate of West Point who is considered one of the Republicans’ top recruits of the cycle. Mr. Peters leads by just one percentage point, 43 percent to 42 percent, among likely voters, a significant narrowing of the race since a Times/Siena survey in June that found Mr. Peters leading, 41-31.
The relatively high number of undecided voters reflects the relatively low profile of the two candidates. Around 20 percent of voters do not have an opinion on either of them. Mr. James’s favorability ratings have increased to 45 percent favorable versus 35 percent unfavorable, up from 36 percent favorable and 29 percent unfavorable in the June survey. Part of Mr. Peters’s weakness is that he has thus far failed to match Mr. Biden’s tallies among nonwhite voters, who disproportionately remain undecided. It remains to be seen whether Mr. James, who is Black, will ultimately make significant inroads among these voters.
A closely fought race in Michigan complicates the Democratic path to flipping control of the Senate, which has looked increasingly plausible as several Senate Republican incumbents have fared worse than the president in surveys. Yet here it is the incumbent Democrat faring worse than Mr. Biden, and a Republican win in Michigan would force Democrats to pick up a win in a state that Mr. Trump won comfortably in 2016, like Iowa or Montana, to win Senate control.
Public opinion polls have been remarkably stable this year, through the pandemic, the economic crisis and social unrest. The surveys of Wisconsin and Michigan were conducted during another tumultuous week in the campaign, and they offered little indication that any of the news had worked to the president’s favor.