The Philadelphia 76ers’ plans for a Center City arena could be batted down by city council unless the team agrees to shell out more through a community benefits agreement, according to a tough round of grilling Wednesday on the $1.3B proposal.

Under fire from council members, representatives for the Sixers testified Tuesday that the organization won’t spend more than $50M on the agreement. The CBA would fund several citywide initiatives and help mitigate the impacts construction could have on surrounding neighborhoods like Chinatown, the center of gravity for opposition to the project.

But the team’s stance imperils the proposal, said Council Member Mark Squilla, who introduced the bills in question and represents the district where the arena would be built.

“It would be a major challenge to have the legislation passed without any changes to the CBA,” he told the Philadelphia Inquirer after the contentious session on Tuesday morning. “I don’t think there right now is enough votes to pass it out of legislation.”

Council Member Isaiah Thomas was one of several lawmakers who requested that the Sixers allocate more money to the CBA. That proposition was declined by David Gould, the chief diversity and impact officer at Harris Blitzer Sports & Entertainment, which owns the Sixers.

Gould said the team should have started with a lower offer for the CBA and worked its way up.

“Potentially shame on us for not starting low and negotiating up,” Gould said.

Thomas also queried why the corporate entity that owns the Sixers would not move from New Jersey to Philadelphia, a request that was echoed by Council member Mike Driscoll. The additional wage tax revenue generated by that proposed move would be worth more than the $50M included in the CBA, Thomas said.

Council President Kenyatta Johnson asked how the Sixers had settled on $50M for the agreement.

“It included looking at comparable projects and what they had provided in the past,” Gould said.

The $50M figure exceeds the amount allocated in CBAs for other similar projects, he said. Gould added that it’s an amount the project can support “economically” once construction is complete.

The arena project will have its first public airing next week as part of a monthlong series of meetings expected to culminate in a December vote.