1. Ally fears that Barak Obama is too inexperienced to run the government and thus needs someone like Biden with his 34 years in congress to hold his hand.

2. Provide an attack dog of sorts that keeps Barak Obama above the fray so that his followers can claim that it is John McCain and the GOP and not Obama and the democrats who are being mean.

3. And the most important fact try and reach out with a great big hand to the Hillary Clinton supporters who are basically the working class, lunch bucket Democrats who believe much more in the old guard Democratic party then they do in the new wave of progressives sweeping themselves into power.