Poor Never-trumpers and their script
The Susan Del Percios of the world are on message that Harris whose poll numbers have been steadily rising "can't get any higher than another point because we live in such a divided country."
Conventional wisdom and recent patterns suggest that "division" is not as rigid as their Del Percio-style thinking. Democrats and progressive issues have been outperforming polls at the ballot box. Republicans continue to move away from Trump. There are no Democrats for Trump to balance or nullify the Republicans for Harris. There's always a lag in polls so it's quite likely the polls are not reflecting the total movement towards the veep.
One could charitably argue that the SD Ps are setting low expectations so Democrats don't get comfortable, but I'm not charitable. I think the dumb from having been republicans hasn't fully washed off.