I think Mac would give us a clean sweep in Arizona, and that would be a definite advantage since AZ is by some standards “trending red” (dem). It’s all about the bell curve - if you can raise the bar there from 55% to 60-62% as McCain can, then you can drag in the inevitable coattail votes.
Problem is, as I outlined above, the party has so little money for the Congressional races, and that’s going to limit us greatly.