Supporters and opponents agree the Senate effort to pass a constitutional amendment banning gay marriage will fall short when a vote comes tomorrow.
Supporters say Congress is the right place to set cultural standards and that traditional marriages are the foundation of healthy societies.
Kansas Senator Sam Brownback says this is "foundational to the society, to the future of the Republic."
Opponents say the proposed amendment is government intrusion at its most personal.
Democrats also charge it is simply an election year effort by the Republican majority to boost support among their conservative base.
Vermont Senator Patrick Leahy says the Constitution "is too important to be used for such a partisan political purpose."