By polling, I mean voter turnout, not which way voters would vote if they do vote.

It’s down to turnout, yes. America does not have mandatory voting, ergo whichever candidate can unify and energize their base will win. Centrists already know who they are voting for, proved by the link you provided.

Biden is seeing constant controversy among likely democrat voters, meanwhile Trump is the current GOP darling.

I really don’t see how the DNC can pull out a win unless they pull out all support from Israel and/or toss Biden and bring on someone younger, with broader appeal and higher energy.