Honestly I don’t know why they even picked him in the first place. He added nothing to the ticket and has been a total embarrassment as vice president.
Obama picked Biden (and will keep him) for the same reason that Nixon kept Agnew on the 1972 ticket.
Nixon knew that Agnew was hated even worse than him. He thought Agnew was his insurance policy against impeachment. That’s why Agnew had to be removed from office first.
Biden is Obama’s firewall. Neither the Republicans or the Democrats will go after him as long as Biden is next in line. Over the last 3 years, I knew that Obama was untouchable. But, if Biden suddenly found his past catching up with him and was threatened by scandal, it would have been because Obama was next.
I hope that we don’t have to worry about it in 2013. But, if Obama cheats or Romney fumbles, Biden will be the canary in the coal mine.