All Polls are Wrong. I don't see why any present poll or polling average should give comfort to the Democratic campaign, because it seems like the real campaign hasn't started. About the only areas that might be of concern to the GOP campaign are seemingly 'iffy' contests for the Senate. I will put down a marker here of so-called swing state polls, and return once all the votes are counted in these (maybe) key races.
Arizona -- today Real Clear Politics aggregate of surveys suggests that Democrat Mark Kelly is ~11% in front of the incumbent GOP senator McSally. Colorado -- RCP's page suggests (on very very scant data) that the incumbent Corey Gardner is ~10% behind challenger John Hickenlooper.
Iowa -- GOP senator Jody Ernst won over her 2014 Democratic opponent by 8.5%. RCP has no information on the present race, but a mid-June Iowa Register survey suggested a three-point advantage to the Democratic candidate Theresa Greenfield.
Maine -- up for re-election is Susan Collins, who won her 2014 contest by 14 points. RCP currently shows a slight lead for her 2020 opponent Sarah Gideon.
Montana -- RCP has no data to present on the race here between Steve Daines and Steve Bullock. But I include this one to test the mettle of the Cook Political Report, who has put the race in the 'toss-up' column.
North Carolina -- the incumbent is Thom Tillis of the GOP. He faces Cal Cunningham. RCP rates this contest a 'toss-up' on scant data.
So, if Arizona, Maine and Colorado are lost by the GOP on November 3, then the Senate will be even-steven, 50 to 50.