Despite a defeat in the Senate yesterday, evangelical Christian groups said they would continue to push for a constitutional amendment to ban same-sex marriage, but some predicted that it would be a 10-year battle.

In the short term, the amendment's religious backers said they would turn their sights toward referendums at the state level. At least nine states, and possibly as many as 12, will have state constitutional amendments against same-sex marriage on the ballot in elections this summer and fall.

Leaders of the Arlington Group, a coalition of 53 religious organizations that have been working together to oppose same-sex marriage, maintained that yesterday's vote was not a major setback but merely a first step in the process of changing the U.S. Constitution, which requires a two-thirds vote in both houses of Congress and ratification by three-quarters of the states.

"I look at this as a 10-year fight. This is Day One," said Charles W. Colson, a Nixon White House staff member who was convicted in the Watergate scandal and now heads Prison Fellowship Ministries.

Colson and other evangelical leaders said the Senate vote achieved several objectives, including energizing grass-roots conservatives, forcing senators to take a stand and forging bonds between the Republican Party and socially conservative black churchgoers who have traditionally been steadfast Democrats.

They acknowledged, however, that their failure to win a simple majority on a procedural vote to cut off Senate debate starkly revealed the obstacles before them. In addition to opposition in Congress, they face strong public reservations about amending the Constitution as well as disagreements among social conservatives over what the amendment should say.

Polls show that support for such an amendment varies greatly, from as low as 36 percent to as high as 60 percent, depending on how the issue is framed, according to an analysis by the nonpartisan Pew Research Center.

Support is higher if the proposed amendment is worded positively -- defining marriage only as a union of a man and a woman -- than if it is worded negatively, as prohibiting same-sex marriage. Support also drops substantially if the public is presented with an alternative to amending the Constitution, such as leaving the issue to the states to decide.

"The polls tell us that most people oppose gay marriage," said Pew pollster Andrew Kohut. "They also tell us that the public is pretty conservative when it comes to fiddling with the old Constitution."

Several conservative Christian leaders said their primary long-term task is to convince Congress and the public that there is no alternative to a federal amendment because state laws and constitutions barring same-sex marriage could be struck down by federal judges.

In the wake of the Senate vote, some Christian groups are calling for passage of a bill introduced by Rep. John N. Hostettler (R-Ind.) that would attempt to strip federal courts of jurisdiction over definitions of marriage.

But Tom Minnery, vice president for public policy at the Colorado-based Focus on the Family, said most evangelical leaders consider that a poor second choice. "Somewhere as a fallback it's a possibility, but the solution is to amend the Constitution," he said.

The Senate vote also showed that after four congressional hearings and a year of debate, the amendment's proponents still have not firmly settled on a text.

In a last-minute bid to increase support for the amendment, some Republican senators on Monday proposed to reduce it to a single sentence: "Marriage in the United States shall consist only of a man and a woman." They suggested eliminating the second sentence, which would prohibit courts from interpreting either the federal or state constitutions to require that "the legal incidents" of marriage be given to same-sex couples.

The wrestling over the text stemmed, in part, from disagreements over the meaning of the second sentence. Some constitutional scholars contend that it would block Vermont-style civil unions, which confer state-level benefits of marriage but not federal protections, such as Social Security. Other scholars say it would allow them.

The wrangling also reflected divisions among the amendment's religious backers. Some members of the Arlington Group, such as the Christian Coalition, favor an amendment that would ban same-sex marriage but not civil unions. Others, such as the Traditional Values Coalition and Concerned Women for America, want to ban both.

Minnery said the refusal of Senate Democrats to allow a vote on an abbreviated text showed that "liberals are scared to death of a one-sentence amendment because they know it would be popular." But he said conservatives also are worried about a single sentence, because they are not sure how courts would interpret it.