The office of the Vice Presidency has NOT, historically, been a place that promotes elevation to the Presidency by election.
We have had 14 Vice Presidents become President, but only five by election–John Adams, Thomas Jefferson, Martin Van Buren, Richard Nixon (eight years later), and George H. W. Bush.
Until the last half century, the thought of a Vice President being the nominee for President in the next or future terms was unthinkable, and only five Vice Presidents have actually been the nominee of a party for President, other than the five mentioned above who won the Presidency, and two of them actually ran on a third party platform.
The five Vice Presidents who ran for President and lost are:
John C. Breckinridge (Southern Democrats 1860)
Henry A. Wallace (Progressive Party 1948)
Hubert Humphrey (Democrats 1968)
Walter Mondale (Democrats 1984)
Al Gore (Democrats 2000)
So these bad odds make it even tougher for Vice President Joe Biden, as he plans a campaign to run for President, with Hillary Clinton standing in his way!