I don't see a big distinction between Biden and Hillary Clinton. In terms of their chances against Trump. The incumbent has a big advantage in no divisive primaries, and the issues he brags about fixing e.g. the economy and Muslim ban. Biden lacks the star power to turn out fringe voters like Sanders, Warren and Trump. I see another drubbing of the Dems in November.
Likability. Trump and Hillary were the most unlikable candidates to be nominated in a long time.
https://fivethirtyeight.com/features/americans-distaste-for-both-trump-and-clinton-is-record-breaking/
Yet Clinton eclipsed Sanders with relative ease. Biden is a fumbler with little charisma. I get why the mainstream Dems might not want Sanders but this will be no cakewalk.
I think I have heard it mentioned that Bernie's loses in the states Biden has won have been worse than when he ran 2016 against Hillary. He is not a flashy charismatic guy. But that is part of his appeal I think. Just an ordinary guy that used to take a train from Wilmington to DC.
The guy is winning in places he did not even campaign. Interestingly that is his potential Achilles. He may assume he does not need to do as much legwork as is necessary. Still in a general election the guy will appeal to western Pennsylvannia types with buyer's remorse.
Did Obama make frantic calls for Clinton behind the scenes? Pre- convention. Without that Biden would be toast. He is hardly his own man.
Biden needs all the help he can get no doubt. Winning where he did not sow portends good things
if he works on it.