Nope, not nearly. About a third of Americans are opposed based on firmly held religious convictions, another third are for them, just to piss off the first third, and the final third are uncomfortable with sanctioning gay relationships right now. There is a brief window of opportunity that is rapidly closing on getting them to the side of the opposition. Right now, the gays are winning the media battle for the mushy middle, it probably won't even be a raging issue by November.
If it keeps conservatives solidly in line behind the President, great. But it will be other things that determine the outcome of the election. Kerry has been quite careful to avoid sounding off too much on this issue, the only real hurdle is how he will handle gay rights activists at his convention this summer. If he can find something to mollify them so they won't make too much trouble for him, he makes it through the minefield on this issue.
LAMDA and ACTUP could all be ON STAGE with EfnK, and his news media propaganda machine would make sure that no American sheeple ever sees it on television. In short, he has no worries. What the commies don't want us to see, we will not see.