New York is one vote away from being the largest state to legalize gay marriage after a Republican state senator declared his support for the legislation.

The bill has not yet been scheduled for a vote, although the New York Times reports, citing unidentified Republican sources that the bill was almost certain to come up for a vote.

All but one member of the Democratic caucus has backed the bill, putting the onus on wavering Republicans to determine the measure's fate. Republican senator Roy McDonald's decision to defy party orthodoxy and pledge a vote in favor gives the bill 31 supporters, one short of the 32 necessary.

Gov. Andrew Cuomo, who has made good on his campaign promise to make gay marriage a priority, formally introduced the legislation yesterday. Cuomo had previously said that he would not advance a bill without being assured of its passage, so his decision to do so reflects a calculation that momentum is building in favor of it.

The legislation has spurred a massive lobbying effort on both sides, prompting impassioned endorsements from elected officials like New York City mayor Michael Bloomberg and staunch opposition from religious figures, including New York Archbishop Timothy Dolan. The bill's passage would represent a stark reversal from 2009, when a Democratically controlled Senate defeated a similar bill 38-to-24.