MOUNT LAUREL, N.J. — The state-to-state march to legalize gay marriage across the left-leaning Northeast has lost more momentum since a major setback three weeks ago at the ballot box in Maine.

Since then, legislatures in New York and New Jersey have failed to schedule long-expected votes on bills to recognize the unions in those states.

“If they are unable to pass gay marriage in New York and New Jersey, combined with the loss in Maine, it will confirm that gay marriage is not the inevitable wave of the future,” said Maggie Gallagher, president of the National Organization for Marriage, which mobilizes social conservatives to fight against same-sex unions.

Gay rights activists insist that’s not the case and say hope is still alive.

“In any civil rights struggle there are going to be periods of creeping and periods of leaping,” said Evan Wolfson, executive director of Freedom to Marry.

This decade has had some of both across the country. The most significant was the leap the issue made from abstraction to reality in 2003 when the Massachusetts Supreme Court ruled that gay couples had the right to get married.

The fallout was widespread: Thirty states have amended their constitutions to specify that marriage can only be between a man and a woman; all but three of those amendments were adopted since the Massachusetts ruling.

But in the Northeast, progress has been much smoother for gay rights advocates.

The Connecticut Supreme Court recognized the marriages last year.

Lawmakers in Vermont, New Hampshire and Maine all adopted gay marriage bills this year. The city council in Washington, D.C., is expected to legalize gay marriage next month.

The only state outside the Northeast that recognizes same-sex marriage is Iowa, where the state Supreme Court mandated it earlier this year.

But last month, voters in Maine — the only Northeastern state where the issue has been put on a ballot — overturned a gay-marriage law before it could take effect.

New York and New Jersey appeared to be the next logical battlegrounds.

Both states have Democratic governors eager to sign bills legalizing gay marriage.

But now it’s not clear if bills will ever get to their desks. There could be national implications if they don’t.