Leaders of the Bush administration- with the notable exceptions of Vice President Dick Cheney and first lady Laura Bush – are about to make another losing try for a constitutional amendment banning same-sex marriage.

Sen. Bill Frist, the majority leader, has slated it for floor action this week, although his office now says only that it will come “sometime in June.”

A similar effort two years ago fell far short in both Senate and House of the two-thirds majority necessary to send it to the states for the three-quarters ratification needed to add it to the constitution. Maine’s two moderate Republican senators, Olympia Snowe and Susan Collins, voted against it. Mr. Cheney expressed opposition. Mrs. Bush was quoted recently as saying, “I don’t think it should be used as a campaign tool, obviously.”

But that’s exactly what it is. Republican congressional majorities face tough midterm elections this fall, with a lame-duck president who has lost popularity. And conservative Christian leaders, who helped re-elect Mr. Bush in 2004, have threatened publicly to withhold their support in November unless Congress does more to oppose same-sex marriage, obscenity and abortion. Mr. Frist, who is pushing the proposed amendment, is considering a run for the presidency.

In 2004, advocates could muster only 50 votes of the required 60 on a cloture effort to end debate. Opponents cast 48 votes. Advocates by this time have picked up a few additional votes. If all senators vote as they did two years ago and new senators vote as expected, the bill will attract 52 votes – far short of the 67 needed to amend the constitution.

Win or lose, the leadership evidently thinks raising the issue will appease the critical religious right and maybe save some of their seats that seem to be in jeopardy.

Playing politics with this highly personal and inflammatory issue is a waste of valuable time yet may not satisfy the religious right anyhow. It seeks to outlaw same-sex civil unions as well. Some strategists want to drop the civil-union provision in hopes of attracting a few more votes.

The two-sentence proposal, titled “the Marriage Protection Amendment,” says: “Marriage in the United States shall consist only of the union of a man and a woman. Neither this Constitution, nor the constitution of any State, shall be construed to require that marriage or the legal incidents thereof be conferred upon any union other than the union of a man and a woman.”

Times have changed. Gay people, who used to lead furtive lives, are out of the closet and exerting their constitutional rights in a social revolution that gains support the further down the voter age demographic one goes. They deserve equal rights, not discrimination by a minority that seeks to use the Constitution as a club to punish them.

As for the protection of marriage, wanting to join an institution is usually a way to honor, not threaten it.