PORTLAND (AP) — For an off-year election, in a state only rarely in the national political spotlight, an upcoming referendum on same-sex marriage has dramatic potential to make history and to roil emotions from coast to coast.

On Nov. 3, Maine voters will become the first in any state with the chance to repeal or uphold a law passed by their Legislature and signed by their governor, legalizing same-sex marriage. The outcome is considered too close to call, and the race is galvanizing activists on both sides of the issue across the country.

The ballot measure, Question One, results from Maine’s provision for a “people’s veto” — any newly passed law can be subject to repeal by voters if enough valid signatures are obtained to trigger a referendum.

“The stakes are very high in Maine, no question about it,” said Frank Schubert, who was hired by gay-marriage opponents in Maine as their top strategist after he coordinated the Proposition 8 campaign last year in California that repealed court-ordered gay marriage there.

Though five other states have legalized same-sex marriage, including four of Maine’s New England neighbors, none has done it with the affirmation of a popular vote. Maine could be the first — a prospect which worries Schubert and his allies.

“It would be first time gay marriage advocates would be able to convince the public to be on their side,” he said. “It would add to their attempt to convince people that it’s inevitable they will win, that it’s just a matter of time.”

Supporters of same-sex marriage, in Maine and elsewhere, are cautiously hopeful of a landmark victory that they believe would have impact in other states, including California. But they acknowledge that defeat — by an electorate known for its independence and moderation — would be crushing.

“If we lose, it will be a day of tremendous grief,” said Judy Chamberlain, who along with her partner of 30 years, Karen Marlin, has been working in the campaign to uphold the marriage law.

Chamberlain, 57, and Marlin, 62, who hope to wed in their church in Brunswick, got engaged in May when the state Senate approved the marriage bill. Marlin replied to Chamberlain’s proposal by text message: “You bet.”

Their 17-year daughter, Nena, adopted from Russia as a toddler, hopes her mothers get the election result they’re working for.

“It would be cool for them,” she said. “They’ve been wanting it so long.”

Among the lawmakers backing the marriage bill was Sen. Larry Bliss, an openly gay Democrat who moved many colleagues with personal stories of raising a family as half of a same-sex couple. Initially, Bliss felt the bill was premature, but changed his mind when his longtime partner quit his job and needed to get on Bliss’s health insurance.

“If he’d been my spouse, it would have been easy,” Bliss said. “Instead the process was appallingly humiliating.”

Many Mainers were surprised by the decision of Democratic Gov. John Baldacci, a Roman Catholic, to sign the bill swiftly on May 6 despite having voiced doubts about same-sex marriage.

The spiritual leader of Maine’s 200,000 Catholics, Portland Bishop Richard Malone, said he was “deeply disappointed” in Baldacci and legislative leaders, and called same-sex marriage “a dangerous sociological experiment.” Catholic churches statewide have taken collections to aid the repeal effort.

Baldacci, a former altar boy, says he is at peace with his decision.

“It’s important to have your own faith and connection to God,” he said in an interview in his statehouse office. “At the same time, it isn’t just that faith you’re the governor of. …You’re governor of all the people.”

When the marriage bill was introduced, Baldacci argued that gay couples could get needed legal rights through civil unions, but his views evolved.

“I was creating a second-class marriage for certain people, which wasn’t right,” he said. “I wasn’t doing my duty to the constitution I swore to uphold.”

Baldacci hopes the campaign, as it gains national attention, will be illuminating and respectful rather than nasty.

“To divide us more, especially during difficult times, would hurt us — leave such scars that they could never be healed,” he said.

Both campaigns depict Maine voters as unlikely to be swayed by out-of-state efforts. Yet the No on One campaign — which supports gay marriage — is welcoming volunteers from afar, and both sides are expected to report substantial out-of-state financial contributions when figures are released next week.

No on One’s supporters include the Human Rights Campaign and other national gay-rights groups. The other side, Stand For Marriage Maine, is getting major assistance from the National Organization for Marriage, which played a key role last year when Proposition 8 quashed a California Supreme Court ruling that briefly legalized same-sex marriage.

Schubert, hired to reprise his role in California, has employed controversial TV ads similar to those which helped sway the Prop 8 vote. Among other claims, the ads assert that “homosexual marriage” will be taught in Maine public schools if Question One loses.

Trying to learn lessons from California, supporters of same-sex marriage have responded with swift rebuttals. Critics of the ads — including Baldacci and top legislative leaders — say Maine has no mandated statewide curriculum addressing marriage, and family life programs adopted by local school boards generally enable parents to exempt their children.

“What Frank Schubert is known for doing is using lies to try to scare people,” said Geoff Kors, executive director of Equality California, who hopes a victory for his gay-rights allies in Maine will bolster efforts to get another referendum on same-sex marriage in California.

Schubert, in a telephone interview, stood by the accuracy of his ads.

“Having an aggressive campaign that focuses on potential consequences, you force people to think about an issue in the way they haven’t before,” he said.

The rival campaign managers have contrasting backgrounds. The No on One leader is Jesse Connolly, 31, who ran Baldacci’s re-election campaign in 2006 and whose father, while a legislator in 1974, led the first attempt to pass a state law protecting gays from bias.

Stand for Marriage’s top leaders are a generation older, both with church backgrounds. Marc Mutty is on leave from his job as public affairs chief for the Catholic diocese, and the Rev. Robert Emrich runs the Maine Jeremiah Project, a conservative Christian coalition.

In a joint interview, Mutty and Emrich said the campaign pits rank-and-file Mainers against political and professional elites.

“Our constituency is Ma and Pa Kettle and Joe Sixpack — people not that engaged in the political process,” said Mutty.

His modest headquarters in a shopping plaza had no sign visible to anyone approaching — a low profile stemming partly from fears of harassment.

“Everywhere we turn, we’re accused of being bigots,” Mutty said, describing initial attempts to secure office space that were rejected based on concerns about security or political backlash.

Emrich said he and his wife have received harassing phone calls and mysterious knocks on their door.

“You don’t want to talk too much about it because you don’t want to scare people off from getting involved,” he said.

Connolly says he wants everyone with his campaign, including out-of-state volunteers, to behave respectfully and he’s skeptical about the alleged harassment.

“The victimization card the other side tries to play doesn’t live up to face value,” he said.

On some matters, Connolly and Mutty agree. They say the vast majority of voters already have made up their minds and believe the battle for an edge in turnout will be pivotal.

Among the most fervent campaigners for gay marriage — working the phones, canvassing face-to-face — are same-sex couples yearning for the right to wed.

Jim Bishop, 62, and Steve Ryan, 56, who both work for a Portland-area low-income housing program, have been partners for 34 years and never before have invested so much time and money — more than $12,000 so far — in a political campaign.

“It’s an emotional issue for me — you realize you’ve been discriminated against your whole life,” said Bishop, who recalled past travels with Ryan when they would pose as brothers to avoid potential hassles.

Beth Allen, 30, and Valerie Frye, 29, just moved into a wood cabin in the hamlet of Fletchers Landing, a three-hour drive northwest of Portland.

They’ve been a couple for three years, working for the same social service agency and sharing care of Allen’s 5-year-old daughter Fiona. They’re engaged to marry next year.

“It makes me nervous what Fiona will have to go through if it doesn’t work out,” Allen said. “She knows we’re a family with two mommies. It doesn’t cross her mind that people would disagree with that.”

Even amid moving and readying Fiona for kindergarten, they’ve made time for their first-ever political campaigning; conversations with potential voters have ranged from warm to cold. Allen said one married woman at a local festival told her icily, “I don’t want you to have what I have.”

Episcopal Bishop Stephen Lane, part of a religious coalition supporting same-sex marriage, anticipates a harrowing election night.

“That will be one of my major concerns on the pastoral level,” he said. “Hopes are so high in the gay and lesbian community that it will be devastating if they lose.”

The campaign seems so close, said University of Maine political scientist Mark Brewer, that he wouldn’t even guess at the outcome.

“Unless someone makes a big mistake, it will all come down to mobilization and turnout,” he said.

Whatever the result, he said it is likely to reverberate nationwide because of the attitude and track record of Maine voters.

“The Maine electorate tends to view itself as independent and pragmatic,” Brewer said. “They like to believe they reach decisions based on good old Yankee common sense.”

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