BIDDEFORD, Maine — Every Oct. 31, trick-or-treaters go knocking on doors. But this weekend, Yalies were knocking on the doors of Maine residents in support of same-sex marriage.

Yale for Maine Equality, an unregistered undergraduate organization, traveled here to canvass against a ballot initiative to ban same-sex marriage. Twenty-four students were out on the streets to encourage voter turnout among Maine residents who have already pledged to vote this Tuesday against Question 1, a proposal to ban same-sex marriage in the state. The debate over Question 1 mirrors last year’s controversy over Proposition 8 in California, which similarly proposed to ban same-sex marriage.

Kate Kraft ’10 and Amalia Skilton ’13, co-presidents of Yale for Maine Equality, said the group first became involved with Question 1 by hosting phone banks in New Haven. Kraft and Skilton said they organized the canvassing trip as part of Drive for Equality, a Maine get-out-the-vote operation, and the NO on 1/Protect Maine Equality statewide campaign. At the orientation before canvassing began, organizers said their goal was to reach voters in their homes and direct them to go to the polls early.

Volunteers started their shifts in Biddeford — one of several canvassing locations throughout the state — at 9 a.m. Saturday, when they were given lists of people who expressed support for marriage equality to phone-bankers, along with addresses and maps. After briefing volunteers on the mission of the campaign, they trained volunteers through scripts on how to approach voters. The weather was relatively warm, the room hectic. Organizers were training volunteers every 30 minutes, volunteers were arranging clipboard packages, and people were on their laptop computers searching the latest news from the polls. When canvassers returned from their shifts, they tallied their findings and handed them to campaign organizers.

Canvassers said they experienced a variety of reactions, from fervent support to slammed doors.

Tory Jeffay ’12 said she was expecting people to be much more unfriendly, and Kate Gonzales ’11 said she was caught off guard by the politeness of most Mainers she canvassed.

“I learned you can’t anticipate what people are going to say,” Gonzales said. “I was surprised by how many people were supportive.”

Skilton said one voter shut the door in her face, but that she also encountered “supportive conversation,” often with members of unlikely demographics such as conservative senior citizens.

She said many of the residents she encountered had a “live and let live” ethos and did not wish to strip people of their rights.

She stressed the importance of working toward marriage equality and getting out of the vote of supporters who have yet to vote.

“It is an issue that affects every Yalie and every citizen in the country,” she said. “Marriage equality is the most important civil rights fight of my lifetime.”

Thirty states have already constitutionally banned same-sex marriage. On May 6, Maine passed a law legalizing same-sex marriages, which would have taken effect in September had a people’s veto — Question 1 — not been filed 13 days later. Should Question 1 be defeated, it would mark the first time in American history that a law allowing same-sex marriage has been legitimized through popular vote. Six states, including Connecticut, have recognized same-sex marriage through court rulings.

Luke Hawbaker ’13, one of the canvassers, said though he gave up Halloween night, the sacrifice was worthwhile. He added that losing the battle for marriage equality “would be a setback [for civil rights] for years to come.”

“I’m very tired,” Elizabeth Freeburg ’13 said on Saturday night. “But I’d do it all over again in a heartbeat.”

Skilton said she does not yet know Yale for Maine Equality’s next step. Still, she said, regardless of Tuesday’s outcome, the group will continue to campaign for other causes, such as repealing the “Don’t Ask, Don’t Tell” military policy.

Correction: Nov. 2, 2009

An earlier version of this article misspelled the name of Tory Jeffay ’12.