Pollsters cannot measure how motivated a voter is to make the trip to the polls.
Here's some math. the pollsters say Mr. Trump has a 40% approval rating. Multiply 235m voters by 0.40 and you get 94m votes.
Mr. Trump did not get that in 2016; he won't get that in 2020.
And then there is the 108m who did not vote in 2016. Mr. Trump hasn't exactyl done things to get any votes FOR him. But AGAINST him. We shall find out on November 3. I say a 70/30 split is possible on election night.
I don't get the sense that the Democrats are overconfident like they were last time. They are playing hard and not making any big mistakes--even if they are happy with their lead.