The Presidential Campaigns on same-sex marriage: The Mainstream View
Here's a video excerpt from the Palin-Biden debate, in which both Sarah Palin and Joe Biden state unequivocally that neither presidential campaign supports any redefinition of marriage.
As I noted in my post below, it's very hard to make John McCain out to be a bigot on this issue. It is much harder, I think, for Prop 8 opponents to make Barack Obama and Joe Biden out to be bigots.
With both presidential campaigns opposed to same-sex marriage, it seems to me that if you vote for Prop 8, you are not an "extremist," or a bigot, or a homophobe. You agree with both presidential candidates, and you are in the mainstream of American thinking on the issue.
UPDATE: I haven't run this down yet, but as I expected, Obama's campaign is backfilling. Reportedly they are saying that although he opposes same-sex marriage, he opposes Prop 8 for reasons specific to that measure.
No matter. The point is that Obama opposes a redefinition of marriage. That takes the "extremist" and "bigot" cards away from Prop 8's opponents.