"I think we should have a national policy on this."
Here comes the pull from the left on same-sex marriage. That's James Clyburn, who ranks 3rd among Democrats in the House.
Marriage is actually unusually hard to handle at the state level — which was why Congress passed the Defense of Marriage Act. If any state permits same-sex marriage, couples who want to marry can travel to that state. Are you going to allow individual states to decide whether to recognize that marriage? DOMA was a decision to say yes, but Obama has said he believes DOMA to be unconstitutional, and he withdrew from defending it in court. Presumably, in appointing federal judges, he hopes to find individuals who share that legal opinion. And the federal government uses marriage status for many purposes. It must either accept the same-sex marriages from the states or not.
So the federalism solution really doesn't work. I know I said — just this morning — that "Leave it to the states is a fine — truly excellent — way to package the issue and set it to the side." It's not as though I'm not aware of the legal problem. I teach the topic in law school classes frequently. It's only that I think the issue can be politically packaged that way. But I must acknowledge that a truly probing questioner would succeed in opening that package back up, and Clyburn is encouraging that inquiry.