Washington ? I took the subway to the culture wars last week. The sidewalk in front of the Massachusetts Statehouse — stop No. 1 on the tourist Freedom Trail — was filled with combatants for and against gay marriage.

Cannons to the right. Cannons to the left. “It’s a sin” volleyed. “Equal rights now” thundered. There were homemade signs that read “Let the people decide” and Magic Marker retorts that said “Don’t Legalize Discrimination.”

Much of Beacon Hill was covered with TV vans. And a foreign correspondent, who had chosen leather chic over Polartec warmth, finished a stand-up in which the only recognizable words were “Boston,” “George Bush,” “John Kerry.”

Meanwhile the Legislature wrangled itself into gridlock over a constitutional amendment to ban the gay marriages ordered by a state Supreme Judicial Court decision. At midnight Thursday, the constitutional convention disbanded until March.

Now, as Massachusetts’ wedding date of May 17 looms, as gay couples in San Francisco commit the civil disobedience of wedding, the common, cringing wisdom is that gay marriage will drive a wedge through the country and the election. Political operatives rub or wring their hands over the image of gay couples celebrating their second-month anniversary as the Democratic National Convention opens here in July. In Washington, supporters of a federal ban are working to reduce the question to an up or down vote.

But what strikes me in all the fury is how the demilitarized zone has grown. And how, in the culture wars, the middle ground has irrevocably shifted.

Was it just a decade ago when domestic partnerships were considered so radical they were restricted to a few liberal hamlets? In 2000, when the Vermont Legislature approved civil unions, people in the Green Mountain State predicted the sky would fall, the milk would curdle and the maple sap would stop running.

Now civil union has become the moderate position. The argument over the rights of gay partners to marital benefits is nearly ceded. The debate is now about names.

In the statehouse, civil union was the alternative favored by legislators who fit no one’s definition of a “Massachusetts liberal.” In Washington, even Colorado Rep. Marilyn Musgrave, the lead sponsor of the federal constitutional amendment banning gay marriage, has said the amendment leaves room for civil unions.

Remember when gay advocates were told that this “extremism” would produce a backlash? Instead, it’s produced astonishing momentum. Marriage in everything but name has become a new norm.

When the gay rights focused on marriage, it changed the image of homosexual America. Today the gay poster couples are middle-aged parents with a kid, a golden retriever and a soccer schedule. The “gay agenda” is a wedding.

No one knows how this issue will play out in the election, but maybe not as darkly as many predict. Polls suggest that many Americans are more ambivalent than polarized. We’ve seen majorities opposed to same-sex marriage and opposed to amendments banning it. The numbers shift with the way the questions are asked.

Kathleen Hall Jamieson of the University of Pennsylvania, who analyzes rhetoric as if it were a basic cell in the body politic, says simply, “The public doesn’t like banning things and the public does like protecting things.”

All in all, Americans don’t want the government to deny individual rights, but they do want it to defend large institutions. In the middle are people who don’t think it’s fair when a gay partner can’t get health coverage. And people who cannot quite put gay and marriage in the same sentence.

In presidential politics, the debate over a federal constitutional amendment will be framed between the rights of individuals and the sanctity of marriage. But both Republicans and Democrats are bidding for property in that demilitarized zone. So Kerry talks about gay rights but doesn’t favor gay marriage. Bush talks about the sanctity of marriage but doesn’t oppose changing laws that give gay couples medical and inheritance rights. Do I hear civil union bells?

Yes, I know that the most fervent on both sides unite in disparaging civil unions. The Family Research Council calls it “counterfeit marriage.” The gay marriage advocates agree — as do I — with the Massachusetts’ Supreme Judicial Court that “separate is seldom, if ever, equal.”

But we are watching how change happens.

In 1948, when California became the first state to strike down a ban on interracial marriages, nine out of 10 Americans were opposed. Sometimes indeed, the milk doesn’t curdle, the world doesn’t fall apart, a “radical” change becomes a new norm.

In the words of one legislator, Robert Havern, “Allow people to get married who love each other. See how it works out. And my guess is it will be the biggest nonevent in the history of Massachusetts.”

Ellen Goodman is a columnist for Washington Post Writers Group.