TRENTON - A crucial New Jersey Senate vote on same-sex marriage, expected to be held today, was called off late yesterday as advocates struggled to find the support needed for passage.

The measure's sponsors, Sens. Raymond Lesniak (D., Union) and Loretta Weinberg (D., Bergen), asked for the delay, hoping the bill would begin moving through the Assembly, where it is believed to have more solid support. But no Assembly hearing has been scheduled.

The maneuvering appeared to be a setback for the same-sex marriage movement, which has been focused on New Jersey since the defeat of a similar measure in New York state last week.

"The 21 votes to pass this, it's not there," said John Tomicki, a leading opponent and president of the Coalition to Preserve and Protect Marriage.

The Senate is seen as the biggest political hurdle to making New Jersey the next state to allow gay and lesbian couples to wed. Some supporters of gay rights had hoped a public vote today could force lawmakers to take a stand and potentially roust the final votes needed.

But several Democrats have come out in opposition to the measure, and others have remained publicly ambivalent, raising questions about its fate. Some gay-rights advocates are wary of a failed public vote, especially in the wake of recent same-sex marriage defeats in Maine and New York.

"I don't know if we'll ever know if we have the votes until the board is open and people actually cast their votes," Lesniak said, adding, "I think it's a 50-50 chance. It's a real toss-up."

Steven Goldstein, executive director of Garden State Equality, said Assembly hearings would give gay and lesbian couples another chance to make their case after some did not get to speak at a Senate committee vote Monday.

"It's not a setback . . . we think it's a good thing," Goldstein said.

Weinberg said the delay should give advocates on both sides "additional time to engage legislators in the dialogue and to understand the amendments that we've put forward."

Senate President Richard J. Codey (D., Essex) agreed to the request for a delay in the upper house, saying in a statement, "I understand their desire to make sure this bill receives the thorough attention it deserves, and therefore I have agreed to postpone [today's] vote until further notice."

The sponsors hoped the bill could receive a hearing in the Assembly Judiciary Committee.

Assembly committees are not due back in Trenton until Jan. 7. Whether the measure begins to move then is up to Assembly Speaker Joseph J. Roberts Jr. (D., Camden).

"While I'm disappointed that the sponsors have decided to delay the Senate vote, I certainly understand the view that the public should have an opportunity to be heard in the Assembly," Roberts said in a statement, adding, "I must emphasize that no hearing has been scheduled and that I am continuing to discuss this issue with our caucus to gauge whether there is enough support for it."

Roberts backs same-sex marriage, but has said he would not post a bill for a vote unless it has the support to pass.

Politically, Assembly lawmakers would be loath to tackle a potentially controversial issue only to see it fail in the Senate - thus so much focus in recent weeks on that chamber.

Democrats in New Jersey, a traditionally liberal state, have wavered on same-sex marriage since losing the governor's race in November.

Lesniak said holding Assembly Judiciary Committee hearings would give that panel the chance to hear the same testimony the Senate Judiciary Committee heard Monday when it narrowly voted to advance the measure.

"We figured it would be better for the bill to be moving in both houses at the same time," Lesniak said.

If the bill is released by the Assembly Judiciary Committee, both the Assembly and the Senate could then vote on the bill. The Senate Judiciary Committee cleared the bill in a 7-6 vote after nearly eight hours of testimony and debate.

The near-term prospects for same-sex marriage in New Jersey hinge on the next few weeks of legislative action. Gov. Corzine has said he will sign the bill if its reaches his desk but Gov.-elect Christopher J. Christie, who takes office Jan. 19, has said he would veto it.

Democrats control the Senate by 23-17, but votes on the bill were not expected to follow party lines. Two Democrats voted against releasing the bill in the Senate Judiciary Committee and one Republican voted in favor.

One opponent, Sen. Gerald Cardinale (R., Bergen), said he had heard of nine Democrats in the Senate who plan to vote against the bill.

Tomicki, a socially conservative opponent, accused Lesniak and Weinberg of trying to use "sleight-of-hand" to move the bill in the Assembly and create the appearance of momentum.

"It is tragic that the legislative leaders are using the legislative process as a propaganda tool, trying in these closing days to create the aura that there is public support for homosexual nuptials," Tomicki said.

New Jersey has allowed civil unions for gay couples for nearly three years, but critics say the unions have failed to give gay couples the same protections offered by marriages, as required by a court ruling.

In testimony Monday, gay and lesbian couples said they had been denied access to their partners in hospitals and benefits such as health insurance under civil unions.

Connecticut, Iowa, Massachusetts, Vermont, and New Hampshire have approved same-sex marriage.

Contact staff writer Adrienne Lu at 609-989-8990 or alu@phillynews.com.