The defeat of same-sex marriage legislation in the New York State Senate last week was a devastating blow to gay rights supporters, leaving many to wonder how the bill could fail after its advocates had expressed confidence in the measure’s passage.

The New York State Senate on Dec. 2 voted 24-38 against the legalization of same-sex marriage, a lopsided margin that raised questions for those who were watching the bill’s progress.

State Sen. Tom Duane, who’s gay, was the prime sponsor of the Senate marriage legislation. He had media outlets he was “optimistic” about the proposal’s chances before senators killed the bill.

Duane, who didn’t respond to DC Agenda’s request for an interview, issued a statement saying he felt “betrayed” following the vote.

“Promises made were not honored,” he said. “The lesbian, gay, bisexual and transgender (LGBT) community, and all fair-minded New Yorkers have been betrayed. I am enraged, deeply disappointed and profoundly saddened by the vote today.”

Groups advocating for passage of the marriage bill included Empire State Pride Agenda and Gill Action Fund. Those organizations didn’t respond to DC Agenda’s request for comment.

Dan Pinello, a gay government professor at the City University of New York, said the Senate was unable to pass the marriage bill because the Democratic Party, which narrowly controls the Senate, 32-30, is “in disarray, basically — not only on this particular policy issue, but more generally.”

“There are a number of factions within the Democratic caucus in the Senate that makes cohesiveness in that caucus extremely difficult, unlike the Republican caucus, which is much more united in its position,” he said. “I think the vote [Dec. 2] reflected that.”

Marty Rouse, the Human Rights Campaign’s national field director, also said he thinks the marriage bill failed because of the politically tenuous situation in the Senate. He noted that Democrats briefly lost control of the chamber in a coup earlier this year before regaining leadership.

“It’s difficult to pass legislation when you have a change in Senate leadership, a new and tenuous Senate majority,” he said. “There is a lot of politics in play in passing any sort of legislation.”

Rouse said the marriage bill failed not because of the merits of the legislation, but because of political issues in the Senate.

“This has much more to do about politics and very little, if anything, to do about the merits of the marriage bill itself,” he said.

The legislation failed in the Senate even though the bill had strong support in the Assembly, which approved the measure for a third time Dec. 2, 88-51. Gov. David Paterson (D) also was a strong advocate for the marriage bill.

Pinello said the legislation failed in the Senate — but passed in the Assembly — because senators “are out of touch with their constituents.”

He said polling data shows a majority of Long Island residents favor same-sex marriage and noted that three-quarters of that region’s Senate delegation voted against the marriage bill.

Eight Democratic senators voted against the marriage bill Wednesday. All Republican senators voted against it.

Jeff Cook, a legislative adviser for the Log Cabin Republicans who had lobbied GOP lawmakers on the bill, said there was no Republican backing because the dissent among Democrats meant GOP support wouldn’t have made a difference.

Before the vote, Cook had said he was expecting Republican votes in favor of the legislation.

“Sadly, we didn’t lose on the merits, but we lost because of politicians’ lack of political courage to do the right thing,” he said. “Seeing insufficient support on the Democratic side, key Republicans communicated that they were unwilling to follow their conscience and take a tough political vote if they couldn’t make the difference on a losing bill.”

Pinello said Republican Assembly member Dede Scozzafava’s recent failed bid for Congress also had an effect on GOP senators. Scozzafava, who has voted in favor of same-sex marriage three times, ran for Congress in a special election this year, but withdrew her candidacy after a third-party conservative candidate challenged her because of her position on marriage, among other issues.

“I think there was some fallout as a result of that on the Senate Republican side,” Pinello said. “I can’t believe that the Republican caucus is so uniformly opposed to marriage equality that not even one or more would have favored it.”

Although the bill was voted down, Pinello said having the vote last week was appropriate because “to keep putting it off is just unacceptable as a political matter.”

“So, now that their votes are recorded, activists can try to target those people — especially in the Democratic Party, but also Republicans — who voted against marriage equality, in next year’s legislative election cycle,” he said.

Asked whether the bill should have come to the floor, Rouse replied, “I’m not going to second guess the decisions that were made.”

But the failed attempt means supporters of same-sex marriage will have to wait before marriage rights for gay couples become available in New York.

Rouse said there is no reason why supporters shouldn’t work to bring the bill up again in the “very near future,” and said it’s possible for Senate leadership to find a way to have another vote within a few weeks.

Another 14 months would be the longest it would take to bring the marriage bill to the floor of the Senate again, Rouse said.

“If we have to have this bill come up after the elections, clearly the 2010 election and who’s running again for office … all of that will be important,” he said. “Supporters of marriage equality and opponents of marriage equality will be focusing like a laser beam on the primary and general elections in 2010.”

Pinello, however, said that 2013 might be a more realistic time for same-sex marriage to pass in New York.

He said after Senate districts are redrawn following the 2010 Census, there would be an opportunity to elect more supporters of same-sex marriage to the Senate in the 2012 elections.

With Democrats in control of both chambers of the New York Legislature, Senate districts could be redrawn in ways that are more favorable to Democrats, meaning more supporters of gay nuptials could be elected to the Senate in 2012 to take office in 2013 and vote for marriage legislation.

“I think it’s possible that there won’t be a favorable vote in the New York State Senate until 2013 on the issue of marriage equality — four years from now,” he said.

Still, Rouse said he was optimistic and he didn’t think there’s “anyone involved in politics in New York State that doesn’t think there is … support for this bill becoming law in the near future.”

He noted that State Sen. Ruben Diaz Sr. was the only lawmaker to speak out against the marriage bill on the Senate floor and no Republicans voiced opposition during debate.

“That tells me there is support for this bill waiting for the right time for this bill to come up,” he said. “And so, for me, it’s not a matter of if this is going to become law, it’s a matter of when this bill is going to become law, and for various reasons, unfortunately, early this week was not the right time.”