There was a buzz among the crowd that packed the auditorium at Braintree Town Hall last January.

A few weeks earlier, national housing developer ZOM Living had proposed what would have been the largest apartment project in the town’s nearly 400-year history — two big buildings with 495 units, taking the place of underused parking lots next to the South Shore Plaza. The residents were there to protest, and Mayor Charles Kokoros was quick to take their side.

“It’s an extreme amount of density. It’s very concerning to me,” he said to applause. “We do not see this as favorable to the town.”

After that night, ZOM’s project was as good as dead.

That January meeting — and Kokoros’s speech — kicked off a rancorous eight-month saga that would pit the mayor and a motivated group of residents against the developer. Town officials considering the proposal were berated at public meetings, with the apartments likened by one protester to arsenic, and signs decrying the “monster project” planted in hundreds of yards. There were accusations of bullying and social media posts claiming Planning Board members were serving various monied interests.

There was enough support, too, in this new-housing-starved corner of the South Shore, that ZOM kept pushing forward. At least until late August, when an unfavorable Planning Board vote threatened to sink the project’s chances of approval by a divided Town Council. Finally, ZOM pulled the plug.

The ugly fracas, observers say, highlights a big reason why it is proving so hard for Greater Boston to build its way out of its massive housing crisis.

Homeowners — particularly those allied with organized neighborhood groups — wield enormous sway in local politics in communities ranging from Boston to suburban Braintree to small towns like Boxford. And when they oppose a housing development that needs special approval by town officials — as most do — the opposition can stop projects in their tracks.

“A particular group of residents took over the conversation on this project,” said Peter Forman, the president of the South Shore Chamber of Commerce, which has generally supported new housing but did not publicly weigh in on ZOM’s proposal. “No matter where the project is or how many units, we should always have a dialogue. These residents prevented that dialogue from happening. And now, there are people in Braintree realizing that one neighborhood group cannot control the destiny of an entire town. You can’t say no to everything.”

ZOM first began laying out its vision to the town’s major players in the spring of 2022. They spent months meeting with Kokoros, Town Council members, and the North Braintree Civic Association to get their feedback.

The idea was, seemingly, simple: By building housing next to the South Shore Plaza, they could help revitalize it.

Braintree’s largest taxpayer, the mall has struggled in recent years, not just with declining foot traffic, but also with a string of violent incidents, including a deadly shooting early last year.

To ZOM, its acres of underused parking lots represented an opportunity to bring the mall back to life, much as new housing has done at shopping centers in Natick and Hanover. Simon Property Group, the retail giant that owns the mall, sent a letter of support.

It also seemed like a particularly good deal for Braintree, some residents said, because the town’s expenses have been routinely outpacing its tax revenue in recent years. The problem is bad enough that the school system went underfunded in the last budget cycle, and a few town councilors signaled support in hopes the project would help reverse that slide.

And so in January, the developer filed plans to build 495 apartments — 180 reserved for seniors — in buildings on the South Shore Plaza’s parking lots. The $200 million project promised to spin off $800,00 in new yearly tax revenue for the town and help address the need for new housing in a community where home prices have soared with demand outpacing supply. A 2017 report found the South Shore needed to add 44,000 units between 2010 and 2030 to keep up with demand.

Within weeks, Kokoros was on that stage, promising civic association members he’d oppose what they’d already begun calling the “monster project,” a catchall for various concerns around traffic, water and sewer infrastructure, and crime.

That was just the beginning.

A few days later, ZOM managing director Jim Dunlop — wearing a crisp suit and glasses — stood in the same auditorium at a public meeting about the project, saying words like “revenue” and “amenities,” and looking and sounding very much like the sort of well-heeled developer some residents love to hate.

It took only a few minutes for the shouting to begin.

“Go back to Maryland,” shouted residents, some of whom questioned his knowledge of Braintree. “We don’t want you here.”

Three hours later, it was clear how the next eight months were going to go. Throngs of angry residents showed up at every meeting related to the project.

“I couldn’t believe it was my town,” said Frank Marinelli, a Braintree land use and zoning attorney who represented ZOM. “Before we could even get before the Planning Board, there were false narratives flying around from the North Braintree Civic Association. Photos of skyscrapers at the site. They have taken such a strident microphone and scared everybody off.”

ZOM has developed thousands of apartments and condos around the United States, and Dunlop has experienced community opposition in the early stages of many of those projects. But, he said, he’s never seen anything like what happened in Braintree.

By early February, monster project signs — printed by the civic association — were appearing in yards across town. Shirts decrying that the project would require a zoning overlay known as a planned unit development — used frequently in towns throughout Greater Boston — became a regular sight at public meetings. The mayor, after visiting a summer block party that featured signs denouncing the development, wrote a thank you note signed #stopmonsterproject.

And behind closed doors, Kokoros was stonewalling.

In a series of meetings with ZOM, the mayor continued to voice his displeasure with the project, and with the idea of putting housing at the South Shore Plaza at all, according to two people with direct knowledge of the meetings who asked to remain anonymous for fear of harming their standing in town.

Later on, he told the developer that if the Town Council voted in favor of the project, he would veto it, the sources said.

“Absolutely, I would’ve vetoed it,” Kokoros said in an interview Saturday.

From the beginning, he said, ZOM’s proposal was well over the amount of housing the area was originally zoned for, and the developer was “totally unrealistic coming to us with 500 units.” He had numerous concerns about the project, particularly around traffic and sewer infrastructure. And, he said, ZOM made the project more controversial by sending residents materials about the town’s economic state, which “was inappropriate.”

“Folks were fighting for what was right,” he said. “But we had a developer that made it a bigger fight. They provoked the residents, and kept pushing on a project that the town didn’t want. And unfortunately for them, they had to withdraw.”

As in most towns around here, developments — particularly projects that don’t meet a site’s underlying zoning — generally face a winding path to approval in Braintree. The town planner, who is hired by the mayor, generally issues recommendations on proposed projects, which the Planning Board considers strongly (a negative report can often sink a project) before making their own recommendation to the nine-member Town Council. The council has the final say, though, in instances like this, where a project requires a zoning change, the mayor can veto it.

Even as Greater Boston wrestles with a housing shortage that has home prices hitting $900,000, Braintree — a Red Line ride from downtown Boston — has built very little. The town’s population grew by nearly 4,000 people in the 2010s, but it added just 775 homes.

And housing efforts in recent years have turned increasingly contentious, often with the same group of residents turning out to slam on the brakes.

First, there was a project filed in 2017 under the state’s 40B law, which allows developers to circumvent local zoning rules in towns where less than 10 percent of housing stock — or 1.5 percent of its land area — is set aside at affordable rents.

Residents spoke out against it, citing many of the same concerns raised against ZOM — traffic, sewer infrastructure, density — and the town’s Zoning Board of Appeals voted to deny the project, prompting a back and forth with the state courts that’s still going on six years later.

Then there was a showdown in 2019 over efforts to simplify the town’s land-use rules, which would’ve amounted to rewriting the zoning code. Some residents, and the civic association, were incensed, saying the new code would allow thousands of new apartments in town. Former mayor Joseph Sullivan halted the process and launched a master planning process with more resident input.

That’s all to say that the civic group, which represents a part of Braintree made up almost entirely of single-family homes, has frequently been a vocal opponent of housing efforts in town.

Civic association president Kelly Moore is quick to defend his group from NIMBY (”Not In My Back Yard”) labels. He also rejects the idea that the region’s housing shortage is a crisis. He says his group has legitimate problems with ZOM’s proposal, and that Simon should draft a master plan for the whole South Shore Plaza site rather than just turning part of it over to a housing developer.

Nearly 500 apartments, or even the 400 and then 300 that ZOM later proposed, he said, would bring new children to town and overload the schools. (Supporters noted that most of the project’s apartments were one- or two-bedroom units, not really designed to attract big families.) He worried it would overload already-busy streets around the South Shore Plaza, and would put a strain on town infrastructure, costing Braintree more money than it would net in tax revenue.

“We’re not antidevelopment, as we’ve been framed,” said Moore. “We do not want to turn into Quincy with the random, aggressive development they’ve had. It’s really important to look at projects like this in the bigger picture and see what potential damage they can do not just to the town, but the neighborhood.”

As meetings about ZOM’s project progressed through the spring and summer, tensions only ratcheted higher.

During one particularly tense Planning Board meeting in May, Moore sparred with board chair Kim Kroha after opponents of the project refused to stop shouting and applauding from the audience. Then, during public comment, he made a speech against the development, even after ZOM had proposed making it smaller.

“My question is how much arsenic is appropriate to drink,” he said. “We have been given a dose. And now the dose is less, but it is still arsenic.”

At another meeting in August, after the developer further reduced the proposal, one resident began to speak about the project’s proximity to a nearby elementary school, suggesting that pedophiles may end up renting the apartments.

“I don’t think many of us like to face the elephant in the room,” he said. “This apartment complex would be a magnet for such individuals.”

To some local officials, comments like that were beyond the pale.

“The rhetoric was disgusting, outright disgusting,” said Town Councilor Joe Reynolds, who supported ZOM’s proposal. “I don’t know how they can sleep at night knowing they lie to their fellow community members.”

But all of the pushback, as well as the negative recommendation from the town planner — who reports to the mayor — weighed on the Planning Board. It was difficult for the project’s supporters to speak up, Kroha said, because they feared retaliation. Ultimately, the Planning Board voted 3-2 to reject the project.

“Every town has people who are concerned with projects, it just happens,” said Kroha. “But I think what was different here is that the group was really given the impression of authority . . . It feels like we lost an opportunity to address some of the big problems with that part of town.”