America ranks almost dead last regarding public acceptance of evolution (currently, the acceptance rate is about 50/50).
According to the Pew Forum, Mormons believe in evolution in fewer numbers than the national average. In fact, only Jehovah's Witnesses are less likely to believe in evolution.
I have not heard Mitt Romney speak directly to the issue of evolution. I understand from reliable sources, however, that he is a "true believer." Even if he doesn't admit it publicly, it is likely that Mitt does not believe in evolution. This is a sad commentary on American politics.