I don't think it will hurt him. I think he is mirroring the sentiments of a lot of people in the US at basically the same pace. If you had asked me the gay marriage question when I was 20 I probably would have recited some passage from the bible. America is changing and pulling away from religion and we want what is right according to common sense and not according to the bible. If he has been struggling because of his religious beliefs, he has done well choosing in favor of justice.
I would bet his team has done the research,and wound out it will in some way help him. If not he wouldn't have done it. You know ALL Politicians say only what they think will help them. Anything to FOOL the people.
Funny how it took him 4 years, until re-election time to endorse gay marriage, but not quite as long to back military families, I think that only took him 2 years! Talk about on the ball!
Don't know and don't really care. I'm a Canadian. I'm more concerned about the Prime Minister.