Unless he has a tip that Hillary is going to jail, he needs to stay out. There's no way his heart can be in it, and even if he does beat her, he's a weaker general election candidate without being significantly different politically. He's a high-risk, no-reward candidate compared to Hil.
Biden
-Isn't tainted by scandal or thought of as corrupt by a majority of Americans
-Has been a popular Vice President, whereas Hillary was a so-so SOS and proved incompetent at her job
-Isn't tied to a political dynasty, which Americans right now are tired of
-Is genuine, blunt, not too politically correct, and can speak off the cuff - which is what American seem to want.
-Has genuine charisma where Hillary does not.
Hillary is divisive even among Democrats. A good chunk of liberal Democrats hate her, and the GOP DESPISES her. With Bernie already helping to deepen the divide in the Democratic party, you'll have low Dem turnout if Hillary is the nominee (because the base won't want her), while you'll have high GOP turnout because Republicans hate her that much. Hillary is sort of our Mitt Romney.
Our Vice President doesn't have these problems. I believe he can not only hold together the "Obama coalition", but also might pick up a few white, blue collar voters too.
