Two factors appear to be driving the close race. The first is apprehension within Biden’s base.
While 95% of self-identified Democrats voted for Biden in 2020, the CNN poll found him winning just 87% of Democrats. The New York Times poll found Biden winning 87% of his 2020 voters, and Trump holding 91% of his. The second is that the polls show Biden significantly underperforming recent elections with nonwhite Americans, mainly Black and Latino voters. After winning 92% of Black voters in 2020, Biden is winning just 71% of them in the Times poll.