Listen, I'm actually sympathetic to the notion that opposing DOMA was a risky move for Bill Clinton in '96. Yes, he was easily beating Dole and could've won anyway. But, risky doesn't have to be fatal, it entails giving your opponent an opening, a chance, particularly when they didn't have one. And there's no question that the marriage issue was a huge weapon for republicans, whether it was big enough to derail Clinton we don't know.
On the other hand, what I am sick and tired of is hearing people defend Clinton based on this false premise that he couldn't veto DOMA without being overridden. This sort of view displays a lack of understanding of national politics and party identification with the president, especially in the last 25 years. This whole theory is built on a premise that the roll call on DOMA is static, that Clinton, a popular (~57% at the time) president and leader of the democratic party, having a different opinion on DOMA would not change the votes of the democrats who voted against it. Thats hogwash.
As soon as Clinton came out in support of DOMA in May, it sapped out the energy of the Democratic Senators to climb up that hill to defeat the measure. If he remained silent, let alone support, there would have been a movement to get the president on the record against the measure and many democrats would've kept their powder dry to see which way he would come out. Now if he came out against DOMA, I don't doubt for a second that there would be tons of pressure for the majority of the democratic caucus to fall in line, cause thats how it works.
There are many democrats in the Senate who have supported Obama policies that they didn't like, whether its liberals on drones or conservadems on the Buffett Rule and the ACA. Clinton wouldn't have gotten 100% of the caucus, but he wouldn't have needed anything close to that to protect a veto.