BY DAVID CRARY

Associated Press

PORTLAND, Maine -- 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 new law can be subject to repeal by voters if enough 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opponents in Maine as their top strategist after he coordinated the Proposition 8 campaign last year in California that repealed court-ordered gay marriage there.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, 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.