Keith Humphreys believes that religion will derail Romney and Huntsman:
When I talk to Christian Evangelical friends who are active in Republican politics, their first concern about Romney is not Massachusetts’ health care program and their first concern about Huntsman is not that he worked for President Obama. Rather, they just don’t feel comfortable with the idea of a Mormon President. They generally do not consider Mormons to be Christian and harbor deep distrust about much of LDS practice and beliefs. This Pew poll is a bit out of date, but check out the subsection on GOP Christian Evangelicals to get a flavor of these attitudes.
I don’t see how a Mormon candidate gets out of closed GOP primaries in states like South Carolina and Pennsylvania which have high proportions of Evangelicals. And it’s even worse when they are two candidates competing for the same subset of such voters who are willing to vote for a Mormon.