Starting with a declaimer of being fairly far left...
Biden is not looking like he has a winning chance. He's barely leading in national polls, but those polls are misleading, as, because of the senate, democrats typically need to win by 2.5-3 points in order to have a shot at the electoral college. So he's behind there.
He's behind in several key states where he needs to win. If you count states where he's down 2 points or less, he BARELY has enough to win. Can't miss a single state.
The debate hurt Biden. This is not a logical contest, it's a popularity one, and Biden is not doing well. I think he's done some great policy things, but that's not how people vote. Democrats have to learn that it's not enough to be "right" if you're going to lose elections.