Polls cannot determine the motivation of the voter. Some voters can be convinced to stay at home on election if they believe their preferred candidate is not worth the vote. Distractions such as kids’ sporting events or a snow storm can derail a trip to the voting booth.
T supporters are very motivated. The D’s have to be careful.
A lot depends on 50% who normally do not vote. If enough has gone on to convince them to make the trip to the polls, they are likely to vote D. A 5% increase in voter turnout could give a D landslide.