Interesting. Take a look at these two statements from Pennsylvania Republican-turned-Democrat Senator Arlen Specter.
On September 2nd, Specter sent this in reply to a constituent who wrote about amending the constitution to ban same-sex marriage.
In 1996, the Congress passed and the President signed into law the Defense of Marriage Act (DOMA). I supported the passage of this legislation. This law has two important facets. First, the law defines marriage for the purpose of the Federal government as a union between one man and one woman. Second, it provides that no state or local jurisdiction may be forced to recognize a legal union created in another state or jurisdiction, if the definition of that union is contradictory to their own.
Specter published an op-ed on Huffington Post this morning though that is a little more thoughtful about DOMA.