(CNN) -- The New Hampshire House of Representatives voted narrowly Thursday to legalize same-sex marriage, putting the state's Legislature on a potential collision course with a governor who has publicly stated his opposition to such unions.
The bill passed by a vote of 186-179. It moves to the state Senate, which is not scheduled to take up the debate before April 9 at the earliest.
New Hampshire Gov. John Lynch, who is on the record as opposing gay and lesbian marriages, has not publicly indicated whether he will veto the measure if it reaches his desk.
"Gov. Lynch has not supported same-sex marriage, but the civil unions bill he signed into law prevents discrimination and provides the same legal protections to all New Hampshire families to the extent that is possible under federal law," said Lynch spokesman Colin Manning.
The three-term Democrat signed the state's current civil unions law in May 2007.
With the step taken by its state House, New Hampshire joins neighboring Vermont on the front lines of one of the country's most emotional social issues.
On Monday, the Vermont Senate also approved a measure legalizing same-sex marriage. Vermont Gov. Jim Douglas, a Republican, has promised to veto the bill if it passes both houses of the Legislature.
Massachusetts and Connecticut are the only states that allow same-sex marriage. Vermont, New Hampshire and New Jersey allow civil unions for gay and lesbian couples.
Vermont made history in 2000 by becoming the first state to approve civil unions for gay and lesbian couples. It did so in response to a ruling by its high court.
To date, however, no state has legalized same-sex marriage without being forced to do so by the courts.
Nationwide, the issue of same-sex marriage remains extremely contentious. A June 2008 CNN/Opinion Research Corp. poll found that 44 percent of adult Americans polled said they believe gay marriage should be recognized by law as valid; 53 percent of those polled were opposed.
The issue took center stage in the nation's most populous state in November, when California voters narrowly approved a proposition amending the state constitution to ban same-sex marriage. California had been issuing marriage licenses to same-sex couples since a May 2008 ruling by the state Supreme Court legalized the unions.
California's high court heard arguments March 5 in a case tackling the constitutionality of the controversial ballot proposition. It has not issued a decision.
The 1996 federal Defense of Marriage Act in effect bars the federal government from recognizing same-sex unions by defining marriage as "a legal union between one man and one woman as husband and wife" and a spouse as "a person of the opposite sex who is a husband or a wife."