In the battle over gay marriage, all eyes are on Maine. Tuesday, the voters will decide on Proposal 1, a ballot initiative that would repeal a Maine law allowing gay marriage. Polls show that voters are nearly evenly divided over the issue, but some suggest that if older voters turn out in droves they could tip the scales in favor of a repeal. Here's why Maine's vote over gay marriage is such a nail-biter:

  • First Show of Popular Support for Gay Marriage  Daniel Chandler of The Nation says "a victory for the "No on 1" campaign would be the nation's first popular vote in support of gay marriage." He says a yes-vote on the proposal will be a huge setback for the gay rights movement across the country.

It would put an end to more than thirty consecutive defeats of marriage equality at the ballot box--including California's Proposition 8 one year ago--as states across the country have passed constitutional amendments defining marriage as between one man and one woman. (A 2006 vote in Arizona which rejected such a constitutional amendment is the only exception, but that was followed by a 2008 measure banning gay marriage which passed by a comfortable margin.) A defeat on Tuesday would be a major blow, reinforcing the argument that gay marriage has been won only through the actions of "liberal elites" in state courts and legislatures.

  • Timing Is Crucial  Abby Goodnough of The New York Times says a rejection of gay marriage by Maine voters could deal another serious blow to a movement that is still "reeling" from defeat in California. "Although Maine’s population is a tiny fraction of California’s and the battle here has been comparatively low profile," she writes, "it comes at a crucial point in the same-sex marriage movement. Still reeling from last year’s defeat in California, gay-rights advocates say a defeat here could further a perception that only judges and politicians embrace same-sex marriage."
  • Momentum  At The Atlantic, Andrew Sullivan says "a victory for equality would be a huge boost to efforts in New York, New Jersey and Washington DC to get equal treatment under the law."
  • Odds Stacked Against Gay Marriage  At Wilshire and Washington, Ted Johnson is concerned that conservatives have the upper hand this year. He says campaigns like Proposal 1 that appeal to anger in a bad economy may be more successful than campaigns that appeal to a voter's sense of equality. "In a dire economy, conservative backlash and other simmering angers will the advantage go to those who can tug at people's personal fears rather than civic values of equality?"
  • It's Close, But Proposal 1 Is Still an Underdog  Nate Silver of FiveThirtyEight says that while "the tight polling, certainly, should keep everybody on their toes," he still thinks Proposal 1 is likely to fail. But, Silver says, it will depend on the turnout:
All the polls show a very low number of undecideds, so like most close elections, it's a question of turnout. And the pollsters have different opinions about what turnout is liable to be. PPP has people under 45 representing about 38 percent of the electorate, whereas Research 2000 has them at 51 percent of the electorate. PPP's figures are a closer match for Maine's 2006 electorate, when 36 percent of voters were 45 or under.