I read the Rasmussen story referenced in your post later today. Without denying the importance of the evangelical base (and the risk that it becomes the conservative equivalent of Organized Labor), a couple of thoughts:
1- It shouldn't surprise anyone that the Republicans would prefer Palin to McCain. He lost! Also, she has charisma, he no longer does. And... . (But as Laura Ingraham noted, that worked with journalists until he was up against real liberals).
2- It also shouldn't surprise anyone that the Republicans would prefer Palin against... anyone. There is no alternative - yet, but we're only two weeks into the Obama Administration.