After weeks of maneuvering and delay, the New Jersey State Senate will finally vote on Thursday on whether to legalize same-sex marriage. The Senate needs to approve the bill, and the General Assembly needs to follow — quickly. Gov. Jon Corzine has pledged to sign the legislation into law; his soon-to-be-successor, Gov.-elect Christopher Christie, has vowed to veto it. The transfer of power takes place in less than two weeks on Jan. 19.

Polls show that a majority of New Jersey’s citizens accept the idea of same-sex marriage. There also is wide agreement that New Jersey’s current civil union law does not live up to the standard of equal protection mandated in 2006 by the New Jersey Supreme Court.

Until just a few months ago, it looked as if legislators would enact a marriage equality bill, likely after the November election. But Democrats in both the Senate and House were spooked by Mr. Corzine’s defeat, and their leaders have since wasted weeks in unseemly squabbling over whether the Senate or Assembly should take up the measure first.

The Senate Judiciary Committee approved the bill last month. And the outgoing Senate president, Richard Codey, a supporter of marriage equality, has now made the right call in scheduling Thursday’s floor vote — despite qualms over whether the measure has enough support at this point to pass. The legislation’s chances would be considerably enhanced if the majority leader, Stephen Sweeney, would use the debate to endorse it and rally wavering fellow Democrats to join him.

Mr. Sweeney, who will succeed Mr. Codey as Senate president this month, has declined to say whether he supports the same-sex marriage bill, raising concerns about how he will exercise his influential new role.

It is not too late for him — and all New Jersey legislators — to show real leadership and stand up for the fundamental rights of New Jersey’s gay and lesbian citizens. If the Legislature does not act now, justice could be delayed for years.