Thousands of people, many of them evangelical Christians, gathered on the Mall yesterday for a three-hour rally to protest same-sex marriage and defend what they call "biblical, traditional marriage."

Standing before huge silhouettes of a man and a woman facing each other, conservative Christian speakers warned that putting same-sex marriage on a legal par with heterosexual marriage would be dangerous to the nation's moral life.

James C. Dobson, chairman of the Colorado-based Focus on the Family, raised cheers at the "Mayday for Marriage" demonstration when he vowed not to let marriage "be thrown on the ash heap of history."

"If marriage means everything, it means nothing," Dobson said. "And we must defend the traditional definition of marriage as being exclusively between one man and one woman."

The event was part of an effort by Christian evangelical leaders and lobbying groups to mobilize religious conservatives as the presidential election nears. Dozens of such efforts are scheduled to take place across the country in the coming weeks.

"We support traditional marriage, and we want our voices heard," said Cindy Hill of Hagerstown, holding a sign that said, "Don't Mess with Marriage."

The part-time bookkeeper attended with her husband, Larry Hill. "The politicians pay attention to numbers, and we want to support our values," she added.

"We believe it's important that the marriage be between men and women only," said Sean Bucek of Baltimore, who was with his wife, Adriana. "Families are falling apart. Children are not being raised up as they should be."

The crowd, which included couples and families with young children, stretched from Seventh Street NW to the merry-go-round in front of the Smithsonian Castle, a distance of about three blocks.

Daryl Bursch, an official with "Mayday for Marriage," estimated attendance between 140,000 and 170,000. U.S. Park Police no longer provides estimates of Mall gatherings.

Along with handwritten signs, some in the audience carried plain wood crosses. Hundreds of umbrellas sprouted when a brief shower passed.

The Rev. Cleveland B. Sparrow Sr., pastor of Sparroworld Baptist Temple of the Church of Jesus Christ, in Northwest Washington, stood near the stage and agreed with everything that was said.

"God created man and woman to be together," he said, "and anything to the contrary to that is not the will of God."

Sparrow was among a number of African Americans in attendance who said the issue of same-sex marriage is causing them to change their traditional political alignments.

The Rev. Harry R. Jackson Jr., senior pastor of Hope Christian Church in Lanham, said in an interview that he voted Democratic in the 2000 presidential election but that this year, he intends to vote for Bush because, "I do believe that Bush's core values are true. . . . The guy's a genuine article in terms of personal faith."

Jackson, who gave the opening prayer for the rally, added, "I may be African American, but I'm not going to be in a box."

The prime mover behind "Mayday for Marriage" is the Rev. Ken Hutcherson, pastor of Antioch Bible Church near Seattle. The former professional football player, married for 19 years, said the rally was "to let everyone know that the sleeping giant has awakened, that you are messing with an issue that the church can rally round."

Hutcherson said that as an African American pastor, he is offended by those who say same-sex marriage is "a civil rights issue," adding that it is "a moral and sexual preference issue."

Parents, Families and Friends of Lesbians and Gays (PFLAG), a gay support group, issued a statement decrying "the misguided efforts of fundamentalist 'leaders' to turn back the clock on fairness and equality."

"When people have a chance to really examine what this is all about, it becomes clear that marriage equality for same-sex couples is sound family policy and sound fiscal policy -- and as we've seen in Massachusetts, the sky has not fallen," said Sam Thoron, PFLAG's national president and father of a lesbian daughter.

Mitra Delaney and husband Jim of Holland, Mich., listen while holding a photo of a traditional wedding.Debbie Polfer of Paso Robles, Calif., prays during the three-hour rally. The "Mayday for Marriage" drew thousands, many of them evangelical Christians, to the Mall.