Why?
The only reason I can think that McCain might have something on Romney is that I suspect he would have an easier time beating Hillary. But the reason is that McCain’s more liberal.
Romney's record is the complete opposite of his rhetoric. He's like the convict who found Jesus right before his parole hearing... "I know I did bad things, but I am a new person. Trust me."
But in the end I will end up voting for any but Giuliani.