Back on Friday, Marc Ambinder made an important point about Rudy and gaining support from the Evangelical community:
He doesn't need more in New Hampshire; He doesn't need more to win a three way race in South Carolina; he has, at the moment, more support from churchgoing protestants than Mitt Romney does, according to Gallup's polling. Not more in Michigan. Not more in Florida. The more doctrinal evangelicals split between Romney and Thompson, the better for Giuliani.
This, I think, is precisely what makes the threat of a third-party spoiler bid against Rudy so real — it's quite possible that he'll win the nomination even if a huge block of GOP primary voters deem him unacceptable. As long as they don't find a way to coordinate their activities they won't necessarily be able to block him. Giuliani has a pretty substantial lead in national polls right now, but he's also never polled better than 35 percent and really only ever broke 30 during the interregnum between when McCain collapsed and Thompson threw his hat in the ring. That could be good enough to get the nomination, but you'd really only need 15-20 percent of that large anti-Rudy vote (i.e., 10 percent or so of Republicans, maybe 3-4 percent of the total population) to get behind a spoiler to make life incredibly difficult for Giuliani in a general election.