For the past four decades, a number of Dedham residents have been trying not only to find a site for a permanent senior center, but support for it as well. They may have a site now, but the support is still a question.

Two recently formed groups — the Dedham Senior Center Foundation and the Senior Center Site Consensus Committee — are at odds over a tentative proposal to build the center on the historic Endicott Estate property.

The proposal, which would raise private funds to refurbish and add on to the town-owned estate’s dilapidated barn, has sparked a debate both about the use of public property and the process for approving projects at the site.

In recent weeks, the two sides have been seeking support in the community. Both say the next steps could take place at a Planning Board meeting this summer or at Special Town Meeting in the fall.

The Council on Aging uses a 2,400-square-foot space on the bottom floor of Traditions of Dedham, a private senior-living facility, for activities and as a refuge during extreme weather conditions for the town’s roughly 6,000 senior citizens. The town’s space, however, doesn’t have a bathroom or running water, said Leanne Jasset, a member of the Dedham Senior Center Foundation board.

Still, in recent months, the Council on Aging and supporters of a new facility for Dedham’s older residents were told that the town’s first priority is a new police station, rather than a senior center, Jasset said.

“We’ve been told that there will be no money earmarked for a senior center for the next several years,” she said. “We decided we could just complain about it or we could be a little more proactive.”

So, the foundation was formed. It raised money to do its own feasibility study, and started a proposal for a privately funded building that would be transferred to the town for maintenance and use.

The Endicott Estate, often referred to as the jewel of Dedham, is a 19th-century mansion situated on 15 acres along East Street. It’s often used for community events, such as concerts and road races, as well as private functions, including weddings.

Management of the estate falls under the purview of Town Administrator Bill Keegan. However, Keegan said, having the senior center built with private funds and then transferred to the town would leave the decision of whether to approve the proposal not entirely up to him.

The town doesn’t know who would be involved in the decision, he said, especially since a formal plan hasn’t been created. Once that happens and town officials know what changes to the estate are proposed and how they would be paid for, they’ll have a better idea of which boards need to give the OK, he said.

“We have not yet received an actual proposal; what’s been presented to us is just a schematic,” Keegan said. “Once we are presented with a formalized plan, we can decide on the details of what’s required for the approval process and proceed from there. But everything is in a preliminary stage right now.”

Earlier this year, the foundation approached the estate’s neighbors with its proposal to add on to the barn, and reportedly told them that because the project would be privately funded, it did not need Town Meeting approval.

In response, the neighbors formed the Senior Center Site Consensus Committee with the hope that by doing so, they could force the foundation to be more public about the proposal, and encourage the town to form its own committee to review the Endicott site, and other possible buildings, independently.

“We all consider ourselves stewards of the estate,” Kathleen Shortman said of her fellow Endicott Estate neighbors. “We also feel there are plenty of options in town that are not being considered, and that the seniors are going for the best spot in town as their first resort instead of what should be the last.”

Both groups have held formal and informal public meetings, written letters to local newspapers, including The Boston Globe, and are gathering signatures to support their positions.

The foundation says that local seniors have waited long enough for a suitable facility, and that using private funds for the project would help the town save money.

The neighbors, who say they need to see a fully formed proposal, note that the estate is on the National Register of Historic Places and shouldn’t be altered.

“Because this is a historic place, we don’t want building of any kind, and once we do build, a precedent is set and the estate will no longer be the estate,” Shortman said.

Both groups said they plan to reach out to the community with information and petitions over the next several weeks.

The foundation plans to meet with the Planning Board, and will continue presenting its idea to neighborhood groups, individuals, and even customers at Wardle’s Pharmacy in Dedham Square, where Jassett works.

“We are pushing to make this as public as possible,” Jasset said, adding that seniors often distribute stickers and information at the pharmacy. “Yes, there is opposition, but that’s what America is all about, and we do want people to make their own decision.”

The Senior Center Site Consensus Committee is gathering signatures for a Town Meeting warrant article that would create a panel made up of various community representatives, not just seniors, to study the issue, organizers said. The article would ask Town Meeting members to decide whether the center should be a town decision or up to the residents who formed the Dedham Senior Center Foundation.

“We agree there should be a senior center, we just think that this decision should be public, following the open meeting laws, and fully formed with clear facts so that we can figure out who will have the final say,” Shortman said.