Gay Marriage Ban
Primarily, I disagree with his position. The marriage of two men or two women threatens my marriage no more than their being gay threatens my heterosexuality. In fact, I would be willing to wager that most homosexual marriages are healthier and more loving that the train-wreck that occupied the White House in the late 90's.
Secondly, and perhaps more importantly, the issue does not require a constitutional amendment. Federalizing the issue, which Bush is doing, is contrary to traditional conservative principle. While I disagree with the position, if it is something that has potential supporters, it should be dealt with on a state-by-state basis, not as a federal constitutional amendment.