If you believe Gallop and the economist he could win the popular vote, wild.
According to the latest Gallup Poll:
The percentage of people who identify as republican, democrat, and independent as of are:
D- 27% R- 28% I- 42%
If you take the most recent Economist/YouGov poll, conducted from Oct 18th to Oct 20th, nationally, which has Biden at 47% and Trump at 40% and break it down by party you get:
Democrats: Biden - 85%, Trump - 4%, not sure - 3%
Republicans: Biden - 5%, Trump - 86%, not sure - 2%
Independents: Biden - 39%, Trump - 42%, not sure 8%
Taking this party breakdown and then applying the Gallup party affiliations to it generates this result:
Trump = (0.04 * 0.27) + (0.86 * 0.28) + (0.42 * 0.42) = 0.428 = 42.8%
Biden = (0.85 * 0.27) + (0.05 * 0.28) + (0.39 * 0.42) = 0.4073 = 40.7%
The poll goes from: Biden - 47%, Trump - 40%
To: Biden - 40.7%, Trump - 42.8%, and that's nation wide.
Quite a high sampling of democrats, I know they use registered voters instead of party averages, but when republicans are winning in terms of new voter registration it's odd to me that they would sample democrats so highly above the national average.