"Electability"

Joe Biden had a long, successful political career in Delaware; in part because he's good at local retail politics, in part because of consistent support from corporations and LLCs that flock to Delaware for tax advantages.  With regard to legislative decisions, Biden's approach has been "go along to get along" — a habit he likes to call "bipartisan cooperation."

Joe and Clarence, 1991

In national contests, Biden has been far less successful, due in large part to a bad case of foot-in-mouth disease.  He is notoriously gaffe-prone, and not especially good at explaining himself afterwards.  Needless to say, political junkies are gleefully anticipating his performance in the upcoming debate.  With nine others on the stage, though, he won't have time to say much of anything at all – so he's likely to survive.

So far, in the current presidential campaign, Biden's missteps have not resulted in any crippling pratfalls, but they haven't passed unnoticed.  For Anita Hill, it was much too little, much too late.  Then, there was his overnight reversal on the Hyde Amendment — just a little too fast to claim he'd "evolved" — and one only can wonder how he'll defend his strong support of the pro-bank, anti-consumer "bankruptcy reform" legislation of 2005.

As for working with arch-segregationists Eastland and Talmadge, he really had no choice: they were senior legislators at the time, and Biden was very junior.  Still, it was totally tone deaf to choose them as his examples: and anyway, they were Democrats.  Couldn't he name any conservative Republicans to trot out as his examples of collegiality, like Ted Stevens or John Tower?  That's what his campaign managers would have advised — if he'd asked.

Yes, it's understandable that many long for the relative sanity of the Obama administration, but too many people had had enough of that by 2015 — and Biden is unlikely to inspire the younger voters Democrats will need to win back the Senate.  Americans wanted change in the last presidential election, and they want it even more this time around.  Biden is just more of the same.