Mitt Romney and Barack Obama respond to the 14-point questionnaire from ScienceDebate.org and Scientific American. IMO, both of them play it fairly safe, with no big surprises on either side. About the most radical statement from Romney is this:
I am not a scientist myself, but my best assessment of the data is that the world is getting warmer, that human activity contributes to that warming, and that policymakers should therefore consider the risk of negative consequences.
Alas, he then proceeds to walk back most of this statement.