President Bush has announced his support for an amendment to the U.S. constitution banning same-sex marriage, and observers say the issue could affect this year?s presidential election by mobilizing activists on both sides. Polls show that most Americans also oppose the marriage of two men or two women. But many gays and lesbians say they deserve the right to civil marriage and some state courts and local officials agree.

Ken Sherrill, a political science professor at Hunter College, and Gerald Otte, a former dancer, have lived together in New York City for 36 years. But it was only last year that they were able to marry, when Canada changed its laws. Ken and Gerald went to Toronto and were married by a judge.

The two men say they were surprised at the depth of feeling it evoked ? emotion that comes through clearly in their home video of the civil ceremony. ?I thought it was going to be kind of a political act, like lots of others that I?ve done,? Ken Sherrill said in an interview at the couple?s Manhattan townhouse, ?in a crazy way, not terribly different from getting arrested in front of the South African consulate, you know, just something that one does to stand up. But it conveyed a huge emotional wallop.? Gerald Otte seconded him: ?It was a shock, we both stood there, and the whole enormity of it just flooded us. You can hear it in our voices. It was an incredibly emotional event.?

They wanted to be married for practical reasons, too. Hundreds of rights and benefits come with civil marriage in the United States, from social security survivor benefits, to the ability to direct the medical care of a spouse in the hospital. And there is marriage as a symbol of equality. As Gerald Otte asserts, ?If they?re going to call a union between a man and a woman marriage, then Ken?s and my union is equally marriage.?

But President Bush and many Americans disagree. ?If we're to prevent the meaning of marriage from being changed forever, our nation must enact a constitutional amendment to protect marriage in America,? Mr. Bush said when he announced his support for a constitutional amendment that would ban same-sex marriage.

It?s the symbol, and even the word ?marriage?, that those on both sides of the issue have come to focus on. The president?s call for an amendment defining marriage as between a man and a woman would not forbid gay civil unions, like those permitted in the state of Vermont. ?The amendment should fully protect marriage,? Mr. Bush said, ?while leaving the state legislatures free to make their own choices in defining legal arrangements other than marriage.?

But others say that would only enshrine second-class status for gay couples. ?There is no other legal mechanism that provides the protections, the responsibility, the security, the safety net that comes with marriage,? says Evan Wolfson, director of Freedom to Marry, a coalition of gay rights groups based in New York. ?Marriage is the word we use in our society. It makes no sense to say that gay couples deserve all the responsibilities, all the protections and all the support of marriage, but we?re going to force them to wait on line at the other side of the government building because we don?t want to give them the equality that government owes to everybody.?

The issue has been in the news for weeks, following actions by judges and local officials in several states and cities, from Massachusetts to California, to permit same-sex weddings ? in part to provide a legal bond for gay couples who are raising children together. Some gay and lesbian parents are rearing children born from previous heterosexual unions, and others have adopted children together. Opponents of gay marriage say that children are best raised in traditional families, with both a mother and father.

Gay parents contend that their families are not so different from those of heterosexual couples. "I think ultimately it?s about creating a loving home and supportive environment for your children,? says Barry Miguelino, who is raising two children, Zev and Summer, with David Strah, his partner of eleven years. David Strah is also the author of Gay Dads, a book about gay male couples creating families through adoption or surrogacy.

David and Barry say that only a union that?s equal to marriage is enough to protect them and their children. ?We don?t care what it?s called as long as the rights are exactly the same,? says David, and Barry adds, ?That?s one of the issues that concerns me, is that along with calling it something else, it will end up with some different configuration.?

But political analysts say the president?s support for a constitutional ban on same-sex marriage is a clear signal he will make it an issue in this year?s presidential campaign. Polls show that as many as two-thirds of Americans also oppose same-sex marriage ? though only about half say they support amending the constitution to ban it. The frontrunner for the Democratic nomination for president, John Kerry, says he favors civil unions and supports neither gay marriage nor a constitutional ban on it.

The outcome of the debate couldn?t mean more to couples like Gerald Otte and Ken Sherrill. Yet as a political scientist who specializes in presidential elections, Mr. Sherrill says he doubts that same-sex marriage will sway this year?s presidential contest one way or the other. ?A very small percentage of people vote on the basis of this kind of issue,? he says. ?Overwhelmingly, people vote on the basis of the economy, jobs, unemployment, war and peace. Those are the things that matter.?