In the battle over gay marriage, both sides contend that time is on their side. But both are raising -- and spending -- money like there is no tomorrow.

The forces arrayed for and against a constitutional amendment to ban same-sex marriage are rapidly becoming institutionalized at both the federal and state levels, according to evangelical Christian groups and gay rights organizations.

A little more than a year ago, each side had a handful of little-known activists. Now mighty coalitions pour millions of dollars into advertising and lobbying. Activists on both sides have begun to speak of the issue as "the new abortion" -- a passionate and uncompromising struggle that will be fought in Congress, the courts and state legislatures, and through referendums for at least a decade to come.

The two sides are also increasingly identified with the Republican and Democratic parties. What began as at least nominally bipartisan alliances are now more polarized groups closely aligned with the campaigns of President Bush and Sen. John F. Kerry (D-Mass.) and their networks of consultants and donors.

"For anybody who thought the culture wars were over, this will reignite them and ensure that they will be here for years and years to come. In that sense, it's very much like the abortion issue," said Michael Cromartie, director of the Evangelical Studies Project at the Ethics and Public Policy Center, a Washington think tank. "New careers on both sides will grow out of this, the polarization will continue and grow, and the room for compromise will diminish."

The transformation of the same-sex marriage debate into a lasting confrontation between two well-oiled political machines has taken place much faster than it did in the case of abortion, some activists said.

The Rev. Richard Land, president of the public policy arm of the 16-million-member Southern Baptist Convention, said it took six years after Roe v. Wade, the U.S. Supreme Court's 1973 decision legalizing abortion, for Roman Catholics, evangelical Protestants and other abortion opponents to join together as the Moral Majority.

By contrast, nine months have passed since Massachusetts's Supreme Judicial Court ruled that gay couples have a right to marry in that state.

The battle lines over same-sex marriage have formed at lightning speed, Land said, because "the wiring was already up and ready to go. The institutional connections, the personal relationships -- it was all built over the last 30 years by the pro-life movement."

Both sides flexed their organizational muscles in mid-July as the Senate debated a constitutional amendment and defeated it, at least temporarily, on a procedural vote.

Supporters of the proposed Federal Marriage Amendment flooded the Senate with phone calls, jamming its voice-mail system for three days. Many senators who opposed the amendment were attacked in half-page advertisements placed in their hometown newspapers by two evangelical Christian groups, Focus on the Family and the Family Research Council.

Opponents of the amendment pounced on a July 11 CNN interview in which Lynne Cheney, the vice president's wife, said, "When it comes to conferring legal status on relationships, that is a matter left to the states." Within a day, the Human Rights Campaign, the nation's largest gay rights group, produced a TV commercial trumpeting Cheney's remarks and plunked down $200,000 to air it in the Washington area and five key senatorial districts.

Steven Fisher, a spokesman for the Human Rights Campaign, said it has 13 full-time lobbyists working on the same-sex marriage issue. It also has generated 1.5 million e-mails, faxes and phone calls to Capitol Hill this year, he said, and has spent since March about $1 million on advertising and another $1 million on lobbying against the proposed constitutional amendment.

Yet Fisher estimated that groups opposing the amendment are financially outgunned by its proponents by a 5 to 1 ratio. According to the Human Rights Campaign's calculations, the nation's major gay rights groups had a combined budget of $51.4 million in 2003, while Christian groups such as Focus on the Family, the Family Research Council and Concerned Women for America reported spending $247 million.

Gary L. Bauer, president of the conservative advocacy group American Values, said: "Our perception would be the exact opposite -- the gay rights groups are able to access a lot of Hollywood money and large donors, and they are able to spend many times more money than what the pro-traditional-marriage side is able to spend."

Bauer agreed, however, that both sides have formidable resources. The Arlington Group, a coalition of evangelical organizations, spent $2 million on newspaper ads in February and March to thank President Bush for his endorsement of the Federal Marriage Amendment. Conservative groups are raising millions more to push for state constitutional amendments barring same-sex marriage and to try to unseat senators who voted against the federal amendment.

For example, Bauer said his political action committee has budgeted $2 million for this year's elections. How senators voted on the proposed amendment "will be a major factor for us in deciding where to put our resources," he said.

Just 18 months ago, the main protagonists in the debate were two small organizations, each run by an energetic lawyer on a shoestring budget. Freedom to Marry, headed by Evan Wolfson, was leading the charge for same-sex couples. The Alliance for Marriage, a bipartisan group of civil rights and religious leaders headed by Matt Daniels, was pushing for a constitutional amendment.

Then came the Massachusetts court's decision in November and the granting of same-sex marriage licenses in San Francisco in February, which brought many more organizations into the fray., the liberal Internet-based group that is working to defeat Bush, spent $147,000 on TV advertising against the federal amendment the week of the vote and has raised $557,000 to support congressional candidates who oppose the amendment.

Another newcomer, the Campaign to Protect the Constitution, is organizing grass-roots efforts against constitutional amendments in key states. With seed money from the Human Rights Campaign, it is shepherded by the Dewey Square Group, a political consulting firm that advises many Democratic candidates and is heavily involved in the Kerry campaign.

On the other side, the Arlington Group, which began a year ago as an informal meeting of about 20 evangelical Christian leaders, has grown to 53 member organizations, with three full-time staff members working out of the Family Research Council's Washington office. Opposition to same-sex marriage "has unified and created a coalition of organizations that is unprecedented," said council President Tony Perkins.

Until the Senate vote, evangelical leaders were bemoaning their supporters' passivity over the Massachusetts court decision. But several said they believed the vote energized grass-roots conservatives.

"We lost the vote, but I'm ecstatic," Land said. "The time lag, the pause between the emergence of this issue and its resonance with our voters is over."

Cheryl Jacques, president of the Human Rights Campaign, said she believes the public is split on the issue, with one-third in favor of legal recognition for same-sex couples, one-third against it and one-third undecided. She and other gay rights leaders have argued that in time, Americans will get used to the idea of same-sex marriages and conclude that they strengthen, not weaken, the institution of marriage.

But Bauer said evangelicals are convinced that the public gradually will decide that courts are changing the definition of marriage and that only a constitutional amendment can protect it. "People will see this as the new abortion in the sense that, once again, unelected judges are remaking America," he said.

About a dozen states are likely to hold referendums on state constitutional amendments against same-sex marriage in primary or general elections this year.

In every state in which a referendum is held, "strong grass-roots organizations will be left behind," Perkins said. "This issue is definitely not going away."

Sen. Patrick J. Leahy (D-Vt.) met with Human Rights Campaign President Cheryl Jacques, right, and Bishop Jane Dixon after proposed constitutional amendment banning same-sex marriage failed to pass the Senate.