Pres. Barack Obama just file a brief in favor of same-sex marriage before the US Supreme Court. His same Dept. of Justice filed a 2009 brief saying exactly the opposite. A President can make a political deal or change his mind, I guess. I post both briefs so that the reader can see how it is all just political opinion.
You can find the same-sex marriage briefs on scotusblog, including the Eagle Forum briefs. All Eagle Forum amicus briefs are here.