CONSIDERING THE volume of work Congress has yet to do before members leave town, the Senate's insistence on considering a constitutional amendment to ban gay marriage is telling. Congress has failed to pass a budget resolution or any appropriations bills and remains deadlocked on such important public policy issues as corporate taxation and class-action reform. Yet today, the Senate will take up a cloture vote on the Federal Marriage Amendment. Everyone knows that, in the Senate, the proposed amendment is well short of the votes needed to send it on to the states; even making it to a vote on the merits is highly unlikely. The reason the Senate is moving forward is politics of a particularly crass and ugly sort: Gay marriage has become a national electoral issue. And Republicans believe it is one that can help President Bush, who has come out in favor of the amendment, and make life difficult for Sen. John F. Kerry (D), who not only opposes it but also hails from the very state -- Massachusetts -- whose highest court provoked the current showdown with a decision legalizing same-sex marriage. Precisely because of the weight conservatives have put on this issue, today's vote, despite its preordained outcome, has become deeply important. It requires senators to take a public stand on a question of deep principle: Are they willing to warp the entire American constitutional structure to prevent people who love one another from marrying?

Notwithstanding all the talk of protecting the sanctity of marriage, that is what this vote is really about. Few issues historically have been more purely committed to state authority in this country's system than family law. Federal law already ensures that no state can be forced to recognize gay marriages performed in another, and the federal government withholds such recognition too. The point of a constitutional amendment is to override the judgments of those states that might choose to permit same-sex marriage. There is no good reason to do this. We support gay marriage, though we have criticized the Massachusetts high court's decision. And if voters object strongly to what their court has done, the decision will not survive. Moreover, for all the hysterics of the proposal's supporters, the prospect of its being exported to other states against the will of their residents seems remote. The Massachusetts decision, in other words, requires no federal response whatsoever -- let alone a grotesque rearrangement of the federal-state relationship.

The combination of this proposal's radicalism and its consideration in the middle of an election year commands a strong rebuke from those members who retain enough shame to oppose a constitutional amendment whose express purpose is to deny equal treatment to U.S. citizens. Even opponents of gay marriage, about which people of conscience legitimately disagree, should balk at this measure, which would prevent a democratic majority in any state ever from recognizing it. A strong vote against the Federal Marriage Amendment would send a powerful message that amending the Constitution is not a solution for every non-problem that generates a bad cause.