According to a CNN poll, 27% of self-identified gay voters supported John McCain in the last presidential election, the highest such figure ever recorded for a GOP candidate. In actuality, the number is likely higher, given that there are presumably many gay people who do not divulge their sexuality to pollsters.
While there are indeed presumably many gay people who do not divulge their sexuality to pollsters, I'm not sure that it's fair to assume that over 27% of those who lie about their orientation when responding to a pollster are McCain voters. How does he know that? The raw numbers- not percentages- would certainly be higher if people did not lie about their orientation. But they would also be higher for Obama, too. If everyone told the truth about their orientation, it's hard to be certain about what percentage would end up being for Obama vs. McCain. Further, the numbers are based on exit polling, which is only done in certain states and only to a small percentage of voters. Extrapolating that to the LGBT universe is a bit of a stretch for me.
Although simplistic given that there are independents, etc., it becomes an interesting discussion over the ideology of closeted people (at least, those who stay in the closet when responding to pollsters). While it's conventional wisdom that there are a lot of closeted gay Republicans, I don't see why there couldn't also be a lot of closeted Democrats. It depends on where they live, workplace, etc. as well.