Supporters of New York's historic vote Friday night in favor of same-sex marriage hailed passage as a sign that similar bills will soon sweep the country.

But the momentum behind same-sex marriage legislation has been anything but steady. While the trend over the past decade is toward granting same-sex marriage rights at the state level, the opposition is still intense and the movement to legalize gay marriage has struggled to break out of the Northeast.

New York, the largest state to approve same-sex marriages, did so after several false starts in recent sessions. Signaling the fight ahead, New York bishops released a statement after the vote saying they were "deeply disappointed and troubled" by the decision, and declared the traditional definition of marriage "cannot change."

New York now joins four other northeastern states -- Massachusetts, Connecticut, New Hampshire and Vermont. But aside from the District of Columbia, other jurisdictions where same-sex marriage was approved subsequently became the scene of monumental backlash and could provide a gauge of how drawn-out and contentious the debate may be as it pushes into new territory.

In Iowa, after the state Supreme Court in 2009 ruled that a ban against same-sex marriage was unlawful, voters ousted the judges responsible for the decision last fall. In California, after the state Supreme Court ruled in favor of same-sex marriage in 2008, voters sought to nullify that decision via ballot measure. The case is still tied up in court.

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Even some northern states have held back. Maine voters in 2009 repealed a law allowing same-sex marriage. Similar measures have failed in New Jersey and Rhode Island, as well as in Maryland.

According to the National Conference of State Legislatures, 37 states have statutory Defense of Marriage laws defining marriage as between a man and a woman.

These roadblocks present a stiff challenge to same-sex marriage advocates as they try to build on the momentum from New York and elsewhere. But in the wake of their victory in Albany, those advocates are expressing greater confidence.

Gov. Andrew Cuomo, at a press conference celebrating the vote, said his state had made a "powerful statement" for people across the country.

"This victory sends a message that marriage equality across the country will be a reality very soon," Human Rights Campaign President Joe Solmonese said.

The Human Rights Campaign, which pushed the New York bill, suggested that the latest vote could compel Maryland, Rhode Island and New Jersey to reconsider. A memo put out by the group noted that Delaware also just passed a civil union law and Pennsylvania is considering a constitutional amendment.

The group also cited marriage ballot measures coming up in Oregon and Maine, as well as court cases challenging same-sex marriage bans, and claimed the impact of the New York vote will be in "changing hearts and minds."

The bill's success this time reflected the powerful support of Cuomo and perhaps a change in public attitudes. Opinion polls for the first time are showing majority support for same-sex marriage, and Congress recently repealed the "don't ask, don't tell" policy that barred gays from serving openly in the military.

In the week leading up to the vote in New York, some Republicans who opposed the bill in 2009 came forward to say they were supporting it for reasons of conscience and a duty to ensure civil rights.

"New York's legislators have taken a courageous step forward, acting on our values as a nation, marking a critical milestone in the ongoing struggle for marriage equality," House Democratic Leader Nancy Pelosi said. "New York will send a message to the entire country -- that the arc of history continues to bend toward justice."

Gay rights advocates are looking to President Obama for support as they push for more legislation. The president, though, has stopped short of fully endorsing same-sex marriage. He says those views are evolving. At a fundraiser in New York City Thursday, the president said gay couples "deserve the same legal rights as every other couple." For now, the president supports civil unions.

The administration, though, earlier this year dropped its efforts to defend the federal Defense of Marriage Act.

The Associated Press contributed to this report.