Holding Renzi’s seat is of paramount concern. Knocking out Mitchell is 2nd, and Giffords 3rd.
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.