"We're just polling — yes or no, not trying to find converts or change people's minds," said Christina Hirst, 28, a photographer with three young children. Hirst and her husband, Justin, 33, a high-school Spanish teacher, said they joined the door-knocking Saturday because they don't want their children hearing about gay relationships at school.

The literature that volunteers distributed was intended to reinforce the campaign's message that the amendment is "pro-marriage and children" instead of anti-gay.

"California should do more to encourage families to stay together," reads the pamphlets illustrated with close-ups of heterosexual couples posed cheek-to-cheek.

Frank Schubert, who is co-managing the Yes on 8 campaign, said the outreach effort is designed to counter the principle message of gay rights advocates, who are portraying the upcoming vote as a matter of fairness and equality.

"They want people to feel like you are a bad person if you support what has been the definition of marriage since the dawn of time," Schubert said. By having face-to-face conversations about why the amendment is necessary, organizers hope to reach potential supporters who may worry that voting for the measure would get them labeled as "bigots or homophobes," he said.

Bumgarner distributed handouts listing "Six Consequences if Proposition 8 Fails" that volunteers were encouraged to use as talking points. They included warnings that ministers who preach against same-sex marriage could be sued for hate speech, churches would be sued for refusing to host wedding ceremonies for gays, and that "children in schools will be taught that same-sex marriage is OK."

The amendment's opponents dispute those claims, saying that the Supreme Court specifically exempted churches from having to participate in same-sex weddings and that nothing in state law requires teachers to discuss marriage — straight or gay — with students.

Recent polls suggest the election could be close. A Field Poll taken last month found that 51 percent of likely voters said they would vote against Proposition 8, while 42 percent said they would vote for it.