A zoning debate in Manhattan's Sutton Place may seem like just another posh neighborhood telling a developer its project is not welcome.

But City Hall is listening for a bellwether in the bickering.

A zoning proposal put forward by residents of the neighborhood may force Mayor Bill de Blasio to finally have to reckon with a much-criticized affordable housing program he pledged to examine 15 months ago, experts said.

Near the beginning of 2017, Gamma Real Estate filed plans for a co-op on Sutton Place. Some nearby residents said the project, which is now slated to be nearly 800 feet high, would tower over the neighborhood and change its character.

“Putting a giant tower in this neighborhood is like dressing a little baby in a black leather jacket,” Minette Greenberg said during a public hearing on the zoning proposal. “I understand that our city needs to expand, but not here, not on Sutton Place.”

A neighborhood group called the East River 50s Alliance studied the local zoning and claimed it would do nothing to stop other skyscrapers from rising on side streets.

The group worked with elected officials to suggest rezoning a 10-block strip. Under their proposal, new structures would be capped at 260 feet, but could be wider and slightly denser than currently allowed if they made space for community facilities such as senior centers.

Jonathan Kalikow, Gamma’s president, said the proposal is a veiled attempt to target his project and protect views at The Sovereign, a 485-foot co-op that stands above nearby buildings. He said The Sovereign is dragging its neighbors into an expensive, meaningless fight.

Alan Kersh, head of the East River 50s Alliance, denied the zoning plan is based out of The Sovereign, noting that close to 2,000 residents in dozens of buildings have backed the proposal.

The alliance’s proposal also takes aim at a 1987 affordable housing initiative that helped Gamma’s project grow.

Gamma acquired the right to add 57,000 square feet to its project by spending $24 million supporting about 25 affordable housing units some 20 blocks south of the site, according to Kalikow.

The city Planning Department said it has begun reviewing that affordable housing program, which allows companies building on some of the city’s most prized properties to enlarge their projects by as much as 20 percent in exchange for financing affordable housing.

Under the alliance’s plan, the 1987 initiative would no longer be available. Instead, a similar city requirement would offer developers a smaller bonus for every square foot of affordable housing they help create.

Kalikow and the city’s planning director have questioned the alliance’s logic. They believe the changes are inappropriate for a built-up area near the city’s core and will eventually prompt developers to migrate to nearby areas with the old, looser requirements, resulting in less affordable housing close to Sutton Place.

“We’ve already spent $24 million on affordable housing,” Kalikow said. “The East River 50s Alliance has spent a total of $0 on affordable housing.”

Frustrations with the old R10 program are shared beyond Sutton Place, according to Moses Gates, director of community planning and design at the Regional Plan Association. He said the old initiative is relatively generous to developers, but has still proven inefficient.

In three decades, the program has created 4,341 affordable units, according to the city.

De Blasio has been under pressure to reform the 1987 program since last year, when the city passed its most robust affordable housing program.

“This administration is committed to ensuring that there is room for our city to house its growing population, and to harnessing all the tools at our disposal to meet the affordable housing needs of New Yorkers,” de Blasio spokeswoman Melissa Grace said in a statement.