That was one of the angles I was perusing with
@Spencer_York ...if poll calculus were underestimating Harris support, wouldn't we be seeing that in early voting? Thus far, there has been a surge in GOP voting nearly across the board--and certainly nation-wide. To Mr. York's point on this, does this pull from election day votes? Maybe, but voting early allows more opportunity to vote, which "should" increase total votes. With GOP appreciably outperforming prior elections on early and mail-in voting, this "should" lead to more GOP votes cast.
In PA, however, GOP does lag Dems in mail-in balloting (there is no in-person early voting in PA). What I am still trying to ascertain is if the GOP is performing better, even if that are not outperforming the Dems.