Andrew Sullivan, for me, nails it on the head:
“There are so many reasons why gay people might vote Republican if the GOP were a conservative party and not a religious one. Small government, individual freedom, low taxes, strong defense: these are values shared by many gay Americans. Personal responsibility is also one of them. When I think of a gay person who lives responsibly, saves his or her money, goes to church, contributes to charity and settles down in a stable relationship, I think: conservative. When such a couple wants to get married, I think: conservative. When such a person decides to serve his country in the military, I think: conservative. But the new Republican base sees all this and thinks: evil.”
That is why I find it very difficult to ever support a Republican candidate. Even if the candidate is obviously personally pro-gay (ie. Rudy Giuliani). The candidate still voluntarily aligned themselves with a political party that routinely uses GLBT Americans as the boogeyman.
(NOTE: Yes, I know there are Democrats who are no better, but I don’t vote for them either)