By Dan Wiessner

ALBANY, June 15 (Reuters) - The New York state Assembly approved same-sex marriage on Wednesday and the bill is likely to face a vote in the Senate on Friday, where it only needs support from one more senator to pass.

The Democrat-dominated Assembly voted 80 to 63 in favor of the marriage equality bill introduced by Governor Andrew Cuomo, a Democrat in his first year in office.

The state-by-state battle over gay marriage has become one of the most contentious U.S. social issues ahead of the 2012 presidential and congressional elections.

"Only second-class states have second-class citizens," said Assemblyman Charles Lavine, a Democrat who voted in favor of legalizing gay marriage.

Connecticut, Iowa, Massachusetts, New Hampshire, Vermont and the District of Columbia allow same-sex marriage, and several other states allow civil unions. The first legal same-sex marriages in the United States took place in Massachusetts in 2004.

New York's Assembly has easily passed a bill legalizing same-sex marriage several times in recent years. But the move was rejected the first time it was voted on by the then Democrat-led Senate in December 2009.

The Senate is now controlled by Republicans and currently 31 of the 62 senators have publicly indicated support.

Senator Ruben Diaz, a Pentecostal minister, is the only Democrat out of the party's 30 senators who does not support same-sex marriage, while Republican senators Jim Alesi and Roy McDonald, have said they will vote in favor of it.

On Tuesday "Sex and the City" actress Cynthia Nixon and New York Ranger ice hockey player Sean Avery lobbied lawmakers in Albany to legalize gay marriage. Nixon has been engaged for two years to a woman and wants to get married in her home state.

Rev. Duane Motley, a Christian lobbyist, said in Albany on Wednesday that legalizing gay marriage would "undermine the stability of our society" because he said a child of a gay couple could only have one biological parent.

If the bill passes, same-sex couples could start marrying in New York 30 days later. The bill does not compel any member of the clergy to conduct a same-sex marriages.

A recent Siena poll found 58 percent of New Yorkers support same-sex marriage. (Writing by Michelle Nichols; Editing by Greg McCune)

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