Over sampling can occur, and you can see that in the internals, but what you can not see is the turnout model used by the polling agencies. You can over sample Dems, but if your turnout model has Dems voting at a lower rate than Reps, it will not be that important.
I feel these polls are using a turnout model that favors Dem turnout by a great deal.
Already debunked. D + turnout not happening in FL and NC.
So what happens to the D + 2012 turnout model assumption if Ds aren’t turning out like they should?
Don’t forget polls can’t measure enthusiasm - which is a predictor of which candidate ultimately wins an election.