The pick shows that McCain understands he needs to shake up the campaign.
According to Slate's collection of national polling data (
http://www.slate.com/id/2195956/) the Dem lead in "safe" electoral votes is 190-78. When states "leaning" in one direction or the other are added, it tightens to 260-191; still the Dems need only 10 of the remaining 84 "toss-up" votes.
The size of Obama's lead is obscured by the more widely reported national-popular-vote polling, which is much closer, and which is, thanks to the electoral college, meaningless.