Normally I would agree with this 100%. However, in this case I will be choosing to vote/not vote McCain based almost exclusively on whom he picks for VP. I'm currently leaning toward a third-party vote, on the principle that a McCain win would destroy the future of the GOP as a conservative base (and would essentially give us a one-party system). However, McCain's VP will be in the best position to define the future of the GOP in 2012 and beyond -- so if it's a conservative, then I'll vote for the future no matter how little I like McCain.
On the other hand, if it's more of the same-old/same-old big government, rudderless GOP establishment (Crist, Romney, etc.), then it solidifies my third-party vote.
My bet is that Juan will pick another boring white guy. But it would make heads spin if he picked a woman!