Mayor Michelle Wu’s proposal to create a nine-person panel to help oversee the city budget process will become law, despite criticism by progressives that it doesn’t go far enough.

Councilor Ricardo Arroyo, who spearheaded an effort to amend Wu’s proposal to add more members to the panel and pay them, said the Wednesday vote failed because three city councilors were absent: Gabriela Coletta, Julia Mejia and Brian Worrell. The final council vote was 6-4.

“This would have passed if we had a full complement of councilors,” Arroyo told GBH News, promising to continue the effort. “It is well within the council’s right to file an ordinance to amend this office now that it is guaranteed to come into existence.”

The vote came more than a year after Boston voters approved a ballot measure to create a participatory budgeting office in 2021.

Wu filed a proposal last December to create the nine-member governing body for the new Office of Participatory Budgeting. It was never acted upon by the council, and will now go into effect under the rules of the city charter.

Members of the Better Budget Alliance, an umbrella coalition that advocated for changes, said the mayor's proposal failed to ensure enough voices of underserved residents.

The mayor's plan “neglects to incorporate best practices that will increase participation of all residents, especially marginalized residents who have not had the chance to participate in city decision-making," the alliance said in a statement.

The lack of compensation for board members, and the lack of an explicit appropriation of city funds for residents to spend under the new model, were also a sticking points.

Councilors Frank Baker, Michael Flaherty, Erin Murphy and Council President Flynn voted against changing Wu's measure as she proposed it during more than a half-hour of floor deliberations.

“This is something that I think waters down our power on the City Council,” Baker said on the floor. “I don’t think that we should have people — without the experience, that don’t know the city departments, that don’t know what we do — having a say on what our budget is.”

Councilors Flynn and Murphy objected to both the tight timeline between the Tuesday council working session and the Wednesday meeting. Flaherty said he preferred Wu’s streamlined approach as a starting point for the new office.

“In order to get started to get this up and running, it always makes sense to keep it simple,” he said.

The amount of money the citizen budgeters will control will be determined by mayor's forthcoming budget.