Mayor Michelle Wu’s $4.2 billion operating budget for fiscal year 2024, which starts on July 1, is set to go into effect without a significant markup from the City Council.

The 12 councillors spent 7.5 hours deliberating, recessing and chiding each other on Wednesday as they attempted five times to override Wu’s various budget vetoes. Only one override cleared the two-thirds vote needed, and it was of dubious legality.

The one successful override seeks to set aside $584,000 to fund a salary increase for municipal security officers.

A Wu spokesperson said the budget, as it stands, funds core city services and public safety, invests in infrastructure and aims to “make Boston the best place in the country to raise a family.” The budget, as Wu originally proposed, expands hours at libraries over the weekends and adds senior programming at community centers, among other investments.

But, the spokesman added, the administration is “reviewing the legal validity of the override provision, as the Boston City Charter places the authority to contract with municipal unions solely with the Administration, and not in the purview of the Council.”

At an unrelated event in West Roxbury, Wu told reporters her administration is negotiating a contract with the municipal security officers and the budget isn’t the venue to determine salary increases. Under the city charter, councillors can vote on a contract once it’s settled, and cannot get involved beforehand.

During the Council’s Wednesday debate, which stretched into the evening hours, Roxbury Councillor Tania Fernandes Anderson, chair of the Council’s budget-writing Ways and Means Committee, proposed the money for municipal officers come from the Boston Police Department’s budget.

That prompted Dorchester Councillor Frank Baker to propose a rewrite, with the $584,000 coming from municipal officers’ overtime budget instead. Earlier in the meeting, he angrily protested the money coming from Boston Police Department, and said councillors were acting like pigs.

After proposing his rewrite, he added, “I’m not a lawyer, I’m not whatever.”

Fernandes Anderson defended her budget process and noted that Baker was not reprimanded by City Council President Ed Flynn for calling councillors “pigs.”

Fernandes Anderson, who said she received verbal abuse and death threats in the last few weeks after proposing to cut Boston Police’s budget by tens of millions of dollars, ultimately agreed to Baker’s amendment.

The other overrides failed because they did not get the eight votes required, as progressives were divided over the proposals, and moderates and conservatives were united in opposition.

Before the 2021 expansion of their budgetary powers, councillors could only approve, reject or reduce whatever the mayor proposed. Now they can amend it, but any additions must be offset by a reduction somewhere else. Vast swathes remain untouchable, including the $1.4 billion budget for public schools and fixed costs such as pensions and debt service, according to independent budget analysts. That left $1.8 billion in accounts for councillors to amend in the fiscal year 2024 budget, according to the Boston Municipal Research Bureau.

Fernandes Anderson first proposed $75 million in budget amendments, with more than $40 million coming from Boston Police accounts. That eventually shrank to $53 million in amendments, with a $31 million cut to police, before councillors voted to send their changes to her desk. The proposal also cut from accounts for public libraries and veterans.

Wu rejected many of the amendments days later, calling the cut to police “illusory” because city officials are “obligated to cover salary and overtime expenses incurred by the department.” The Wu administration has pursued reforms through police contract negotiations, but public safety unions have historically resisted attempts at reform and continue to do so.

A similar budget fight played out in 2022, the first year councillors had the expanded powers. Councillors sought to cut police overtime despite the law calling for it to be paid out. Wu vetoed that effort as well, saying it was a “false reduction.”

On Wednesday, as the budget debate was getting underway, Fernandes Anderson asked colleagues and constituents to refrain from using violent language and coordinating police officers in response to the proposed cuts.

“I’d like to remind the public I am just a regular person,” said Fernandes Anderson, who is the Council’s first Muslim American.

Referring to the various disagreements councillors have had over the last two years, she said, “some people are more conservative and some are more progressive, that’s all.”