Worse. He'd have even more "base" problems than McCain, he doesn't have half of McCain's appeal in Appalachia, and I see him crashing after the financial crisis. He'd also do even worse in Massachusetts than McCain did.
Romney had the support of people like Coulter, Limbaugh, and DeMint. I think he'd have had less problems than McCain.
I know that, but I still think Romney would prove unpalatable to Republican "base" voters. He did lose the conservative vote in the 2008 primary despite his prominent supporters.