“The New York City Board of Elections’ decision was theirs to make, but we believe sensitive voter information should always be protected,” Caitlin Girouard, a spokeswoman for Mr. Cuomo, said in a statement. She added, “When it comes to the current administration, we need to be extra vigilant to ensure New Yorkers’ information isn’t being used for politically motivated ill will.”

In New York, anyone can request comprehensive voter data from the state or local Board of Elections, which usually provides the information on a compact disc. Political parties have long used the information to target their fliers, phone calls and door-knocking campaigns.

But Albert Fox Cahn, the executive director of the Surveillance Technology Oversight Project, a privacy advocacy group, said there was a “big difference” between information that is technically public as a matter of law, and functionally and immediately available to anybody who wants it.

“It would be incredibly easy for anyone and everyone to simply take those documents and use them for whatever purposes they want,” he said.

The city’s decision, which was reported by WNYC, comes amid the growing availability of data, election-related or otherwise, and growing pushes to contain it. Several local or state parties, including in New York, have angered voters by sending out fliers warning them that their voting history is public record. Apps now enable voters to see which of their friends and acquaintances voted in the last election and to prod them to do so again — or shame them if they do not.