What happens if Bill Clinton vetoes the Defense of Marriage act in 1996? Is the veto overridden? Is there a push for a constitutional amendment like there was in the early 2000s? How does this impact the 1996 election, if at all as I doubt Clinton would lose on this alone.
(1) Yes, of course it is overridden. It passed the Senate by 85-14 and the House by 342-67.
https://en.wikipedia.org/wiki/Defense_of_Marriage_Act
(2) It is hard for me to see a push for a constitutional amendment coming anywhere near succeeding so long as the veto is overridden and the Act is not found unconstitutional by the Supreme Court (eventually, it will be, of course, but only many years later andafter a large change in public opinion on the issue).
(3) I doubt that this alone will defeat Clinton but it will definitely hurt him. It is really almost inconceivable that Clinton would veto it, anyway, given the state of public opinion at the time and the fact that he could justify his refusal to veto as allegedly necessary to head off a constitutional amendment.