PORTLAND — The City Council late Monday night approved expanding a required buffer between large music venues, which — barring legal challenges — will permanently halt the controversial 3,300-seat Portland Music Hall project.

After months of lead-up, officials faced a conflict between a local developer, Mile Marker Investments, that has followed the city’s development rules and a public that has serious concerns with the developer’s chosen business partner, Live Nation.

The venue proposed at the corner of Cumberland Avenue and Myrtle Street next to Merrill Auditorium has faced significant resistance, both from members of the city’s music scene, who have rallied against Live Nation’s business practices, and residents concerned about increased traffic and safety near City Hall.

However, members of the development team and Portland’s business community framed the debate Monday as precedent-setting for a city that needs increased economic activity, especially to sustain downtown businesses.

The expanded buffer between venues with a capacity of more than 1,000 people was first brought forward by Councilors Wes Pelletier and Pious Ali in response to what they called “widespread constituent concerns” about having multiple large venues in close proximity. Staff has said a buffer of that size would kill the project and block new large venues from much of the downtown.

The 5-4 vote in favor took place after roughly three hours of public comment, debate and amendments. A few dozen people spoke on the issue, touching on everything from concerns over congestion and Live Nation’s predatory business practices to development precedent and the need to bring more life to Portland’s downtown.

Councilors April Fournier, Ben Grant and Anna Bullett joined Pelletier and Ali in voting in favor. Mayor Mark Dion and councilors Regina Phillips, Kate Sykes and Sarah Michniewicz were opposed.

The buffer language, as well as the termination of a moratorium on large venues, will become effective May 27.

It wasn’t immediately clear whether the development team plans legal challenges to the council’s decision.

On Tuesday, the Maine Music Alliance, which organized local opposition to the project, appeared to be preparing for a potential legal battle by urging supporters to donate to continue the fight.

“The next steps will require money,” a post said.

Representatives from Mile Marker Investments did not respond to requests for comment Tuesday.

In a statement early Tuesday, the Maine Music Alliance called the council’s decision “a truly historic moment, not just for our local scene, but for the broader independent music community across the country. Portland, Maine has shown what is possible when communities stand together.”

Last month, the Portland Planning Board unanimously recommended against mandating the larger buffer, with members calling it arbitrary and out of line with the city’s long-term planning.

However, Councilor Grant said Monday that he disagreed with the planning board opinion, arguing that a buffer mitigating traffic congestion, parking and safety would be consistent with the city’s comprehensive plan. He also said he disagreed that government “should be done on autopilot.”

Dion said his vote was “in favor of an economic future for this city.”

Representatives from Mile Marker Investments and supporters of the project have said the buffer was simply designed to kill the venue, which otherwise complied with all city zoning regulations.

Mile Market President Howard Goldenfarb told the audience that Live Nation has been doing business in Portland for 50 years, with its shows frequently taking place at Merrill Auditorium, Cross Insurance Arena and Aura.

Goldenfarb said 22 of the 30 development projects he’s overseen in Portland are within a few blocks of City Hall.

“This city has changed,” he said. “What we’ll do for Portland will benefit the city for years to come, and I believe will be a site the city will be proud of.”

The development team has said the venue will create 250 full- and part-time jobs. Several workers from the International Alliance of Theatrical Stage Employees, a union representing over 100 stagehands, technicians and entertainment workers throughout Maine, spoke in support of the project Monday.

But others like Peter McLaughlin, board president of the Maine Music Alliance and a longtime staff member at Space, said while they “know and respect the labor concerns,” the decision was bigger than that.

“How much of our culture are we willing to gamble?” he said. “A Walmart at the former Brian Boru would bring a lot of new jobs too.”

Opponents felt some vindication earlier this month when a New York jury found that Live Nation and its subsidiary Ticketmaster have been operating as an illegal monopoly, stifling competition and driving up ticket prices. And while the ruling’s impact to consumers and venues may not be known for some time, it was clear that it inspired public comment Monday.

“I am here on behalf of Portlanders who choose local flavor instead of corporate slop,” said one commenter, who identified themselves as Jules.

Restaurant owners and members of the business community also spoke against the buffer, saying it would send the wrong message to developers that might consider approaching the city with projects.

Nate Dubois, developer of the Francis and Longfellow hotels, said the expanded buffer would be “devastating” for future development in “a city that needs housing and to fill vacant spaces.”

“The economic reality of the restaurant business downtown is stark,” said Tom Barr, owner of Lazzari on Congress Street. “We need people brought into town. Whether it’s Live Nation or anyone else, these economic drivers are important, and it’s the difference between people keeping their jobs.”

Emilia Dahlin, a local musician, said voting against the project would send the message that the city doesn’t do business with companies like Live Nation and pushed back on the idea that it would set a precedent that would stifle development.

At one point, Councilor Michniewicz proposed an amended 250-foot buffer, which she said could address some safety concerns around patrons exiting both venues at the same time but would not kill the project. Despite gaining some traction among councilors calling it a compromise, the amendment failed, 5-4.