Biden was at rock bottom in the polls. When Harris replaced him, there was nowhere but up in the polls because Dems were happy he wasn’t going to be the nominee."Poll looks accurate"??????? How do you know? Seriously ... how do you know?
What I see is this. When Harris became the candidate, she instantly closed the polling gap that previously existed between Biden and Trump. That's not one poll showing this, it's numerous polls; each varying a bit in the point spread, each differing a bit in its methodology, each with its history that can be evaluated. But as a group, the polls clearly showed Harris obliterated the lead Trump previously enjoyed.
Up to and shortly after the Democratic convention, the polls, as a group, showed Harris holding a slight lead, but within the margin of error. Currently, that lead has faded a bit and it seems the two major candidates are essentially tied in the polls.
I don't know if that will hold or not. There is no way to know. At this point, and unless something changes big time, there is little any individual poll or even a group of polls can tell us about the November election outcome.
That being the case, the Trump/Harris debate Tuesday night is a very important event. It is likely to be widely viewed and it may sway the opinions of millions of Americans.
That rise in the polls for her had partly to to with that and a “response bias “ from poll takers who didn’t previously want to answer the phone but were now more willing.
Also push polls by pollsters to feed a narrative.