Fate of Maryland Same-Sex Marriage Ballot Measure Is Uncertain

For the first time since President Obama endorsed same-sex marriage, four states will ask voters to decide Tuesday whether it is legal, presenting the latest opportunity for supporters to overcome a losing record of appealing directly to voters through referendums.

Supporters of Maryland's same-sex marriage law hope to parlay the backing of Mr. Obama, who is expected to win the state, into a victory. Voters have backed constitutional amendments limiting marriage to a man and a woman in more than 30 states. If efforts to legalize marriage for gay and lesbian couples in any of the four states succeed Tuesday, it will be the first time that same-sex marriage is legalized by ballot measure.

Six states and Washington, D.C., have legalized same-sex marriage by legislation or a judicial ruling. Following suit, the Maryland and Washington State Legislatures passed laws approving it this year, only to face challenges from opponents who forced referendums on Election Day . Maine, where voters repealed the state's same-sex marriage law in 2009, and Minnesota will also ask voters whether same-sex marriage should be legal.

The Obama campaign announced the president's support for Maryland's law in October as Marylanders for Marriage Equality began broadcasting a radio advertisement featuring Mr. Obama's endorsement of same-sex marriage.

“I think President Obama's endorsement has been a significant factor in more conversations being had in all communities, including the African-American community,” said Kevin Nix, communications director of Marylanders for Marriage Equality, adding, “The needle has moved.”

But even with the president's support, whether the law will survive Election Day is unclear. Recent polls show a close race, and some experts caution that they may be misleading anyway as voters may be hesitant to voice their opposition to the rights of others, with the vote against legali zation often undercounted in polls.

A recent poll by The Baltimore Sun showed likely voters were evenly split on Maryland's referendum. Unlike a Washington Post poll about a week earlier - which showed that likely voters favored the law 52 percent to 43 percent - the Baltimore Sun poll did not use the ballot's wording, highlighting the challenge of polling on ballot measures, which pollsters sometimes rephrase to make them easier to understand in phone surveys. Explaining that opponents had petitioned to get the law on the ballot after it was approved by the legislature and Gov. Martin O'Malley, the Baltimore Sun's poll asked simply, “In November, will you vote to make same-sex marriage legal or illegal in Maryland?” In response, 46 percent said legal while 47 percent said illegal.

In Maryland, which has one of the largest black populations in the country, it's been a fight for black voters. Both sides have featured black ministers and civil rights leaders in their campaign ads. The Maryland Marriage Alliance, the campaign opposing the state's same-sex marriage law, recently aired a radio commercial featuring Alveda King, niece of the Rev. Dr. Martin Luther King Jr. and a minister, rejecting comparisons between the civil rights movement and efforts to legalize marriage for gay and lesbian couples and arguing Maryland already has protections for them

“It is possible to be tolerant of gay and lesbian rights without redefining marriage, God's holy union,” she said in the commercial.

The Maryland Marriage Alliance could not be reached for comment.

In addition to Mr. Obama, the N.A.A.C.P. came out in favor of same-sex marriage this year, and local chapters have been especially active in Maryland, Mr. Nix said. But the Baltimore Sun poll in October showed 50 percent of black voters oppose the law, while 42 percent support it.

Polls show young people are among the strongest supporters of the ballot measures, particularly in Maryland and Washington State. A Baltimore Sun poll in September showed that 61 percent of voters under the age of 35 favor Maryland's law, while just 22 percent oppose it. A recent KCTS 9 Washington poll reported more than 70 percent of registered Washington State voters ages 18 to 29 support the ballot referendum there, where polls show that voters are likely to uphold the state's law legalizing same-sex marriage.

But young voters - who tend to support same-sex marriage in higher numbers than older voters but also tend to vote in lower numbers - are not the only reason the polls are close. A study released in October found that support nationwide for legalizing marriage for gay and lesbian couples has increased across the board since 2004, with even evangelical Protestants expressing stronger support. Third Way, the Washington, D.C.-based research institute that conducted the study, attributed 75 percent of the growth in support to people's changing their minds on the issue.

With the countdown to Election Day down to hours, both sides in Maryland are making their closing arguments to voters. In a commercial released Friday, the Maryland Marriage Alliance warns voters that the portions of the law purporting to protect religious organizations that oppose same-sex marriage have harmful loopholes and that the law will hurt parents' rights to decide what their children are taught in school about same-sex marriage.

Mr. O'Malley, who has thrown his support behind the law he signed, will attend Marylanders for Marriage Equality's election night event in Baltimore, and Mr. Nix is hopeful that they will have reason to celebrate.

“The momentum is on our side,” he said. “I think it's still going to be a close race, but I think we can pull it out.”