New Hampshire's Senate passed a bill on Wednesday that would legalize same-sex marriage after an amendment was added that prohibits polygamy and marriage of family members, among other measures.
Governor John Lynch has not indicated whether he will veto the bill, which passed in a 13-11 vote and would make New Hampshire the nation's fifth state where gay marriage is legal. But the Democrat has expressed opposition to the measure.
The bill passed the state's House of Representatives on March 26 but looked set for near certain defeat in the Senate before the amendment, which appeared to mollify some critics in the Democrat-controlled chamber.
The last-minute changes to the legislation would allow clergy to decline to marry homosexual couples and give couples the freedom to either keep the words "bride" and "groom" on marriage licenses, or simply use the word "spouse" instead.
Because the Senate and House passed separate versions they must resolve their differences before the bill can go to the governor, who in 2007 signed a law recognizing same-sex civil unions, making New Hampshire the fourth state to do so.
Lynch has said the word marriage should be reserved for a traditional heterosexual relationship.
Gay marriage made big inroads this month when, in a single week, Iowa and Vermont joined Massachusetts and Connecticut in allowing gay couples to legally wed. On Tuesday, a joint judiciary committee in neighboring Maine's legislature approved a bill to allow same-sex marriage. Maine's House and Senate could vote on the measure as early as next week.
In California, gay marriage advocates are hoping to overturn Proposition 8, the constitutional amendment that banned gay marriage there, in the state's highest court.
New Hampshire state Senator Lou D'Allesandro was the only Democrat to side with 10 Republicans against the legislation, which would redefine marriage to include same-sex couples. He cited his "traditional family values."
Democratic state Senator Deborah Reynolds, who opposed the bill at committee level, changed her vote after the amendment.
"This is a compromise that is respectful to both sides of this debate and meets our shared goal of equality under state law for all the people of New Hampshire," Reynolds said.
"It honors the religious beliefs of many of our constituents and gives denominations clear authority to decide whether to bless any marriage in this state according to their principles and beliefs."