Abby Goodnough / New York Times News Service

As same-sex marriage supporters celebrate victories in Washington and Maryland this month, they are keeping a wary eye on New Hampshire, where lawmakers may soon vote to repeal the state’s 2-year-old law allowing gay and lesbian couples to wed.

A repeal bill appears to have a good chance of passing in the state House and Senate, which are both controlled by Republicans. The bigger question is whether they can muster enough votes to overcome a promised veto from Gov. John Lynch, a Democrat.

Based on party lines, House and Senate Republicans both have veto-proof majorities. But this is an issue where party allegiance gets muddy.

In a state whose “Live Free or Die” motto figures into many a policy decision, even many opponents of same-sex marriage wish the issue would just disappear. Republican lawmakers with libertarian leanings, a sizable group, seem especially unhappy to be facing a repeal vote, as well as those who maintain that cutting spending should be the Legislature’s sole concern. Both groups appear worried about a backlash from their constituents.

Rep. Andrew Manuse, a Republican, said in an email that he would support a repeal because he objected to government “using its power to redefine a religious, social and societal institution.” But he added, “I really am not focusing on this issue.”

Should the repeal pass, New Hampshire would be the first state in which a legislature has reversed itself on the issue of same-sex marriage.

In Maine, voters repealed a marriage law through a referendum in November 2009, shortly after the Legislature approved it. This fall, a ballot initiative will ask voters to make same-sex marriage legal again. The California Supreme Court ruled in 2008 that same-sex couples there had a right to marry, but voters banned same-sex marriage in an initiative later that year. The issue remains in court.

In a recent poll by the University of New Hampshire Survey Center, 59 percent of respondents were either strongly or somewhat opposed to repealing the law, while 32 percent said they supported repeal.

Rep. David Bates, a Republican, filed the repeal bill in January 2011, shortly after the GOP took control of the Legislature. But House leaders postponed a vote, saying they needed to focus on the budget. Under legislative rules, the bill must come up for a vote this year, although lawmakers could vote to table it again.