Voters on Tuesday soundly rejected a referendum for a constitutional convention, dealing a victory to the coalition of labor unions, environmental organizations and other interest groups that had opposed it.

The referendum was declared defeated less than an hour after polls closed. It falls within an historical rejection of the convention referendum, which voters generally have not approved when given the opportunity.

Holding a convention had been staunchly opposed by labor groups, who worried rights such as collective bargaining would be impacted or potentially weakened if a convention is held. Environmental groups fretted over the status of “forever wild” conservation requirements in the constitution for protected lands in the Adirondacks and Catskills.

“This is a defining moment for the labor movement as it demonstrates what can be accomplished when we all work together, from the public sector, private sector and building trades unions, to the Central Labor Councils and Area Labor Federations,” said AFL-CIO President Mario Cilento.

The groups, through a coalition called New Yorkers Against Corruption, funded an ad campaign opposing the referendum. Some of the concerns — such as infringing on pensions benefits — were overstated. Pensions are protected in the U.S. Constitution.

At the same time, legislative leaders from both parties in Albany feared the convention and the election of delegates would be fueled by well-funded outside groups that can spend unlimited sums of money.

On Monday, Governor Andrew Cuomo, who had previously expressed support for a convention and an overhaul of the delegate process, said through a spokeswoman he would vote no on the referendum.

On the side favoring a convention was a mostly underfunded collection of activists for good government and reform, who had hoped a convention would stir needed changes to the structure of state government and the funding of political campaigns.

They had framed the convention as a once-in-a-generation chance to change a state government that has been beset by corruption and dysfunction.

But those supporters will have to wait until 2037, when the next referendum is scheduled to be held.

“The defeat of the Constitutional Convention is a triumph for all of the enemies of reform in Albany: Andrew Cuomo, the political bosses in the State Legislature, and the lobbyists and special interests who thrive in New York’s pay for play culture of corruption,” said Bill Samuels, the Democratic activist who had supported the referendum, with the hope of ushering in campaign finance and ethics reforms.

“The Constitutional Convention movement was always about fundamentally reforming our broken system and transforming the state’s government from an embarrassment into a proud model for the rest of the nation.”