Unless the District government takes in about $135 million more than expected next year, its police force will drop below a level that Chief Cathy L. Lanier has said could cause “trouble.”

That is one consequence of the D.C. Council’s second and final vote on the $10.8 billion city budget Tuesday. Several provisions in the spending plan, including police hiring, remain contingent on new revenue that could be certified next week.

Because of an improving economy, Chief Financial Officer Natwar M. Gandhi is expected to announce an upgrade in anticipated revenue for the new fiscal year, which begins Oct. 1. But no lawmaker is certain how much new money will be available.

“That’s like the magical number,” said D.C. Council Chairman Kwame R. Brown (D), who added that he expected an uptick but “how much, we don’t know.”

The council has chosen to designate in advance how that money will be spent. In May, the council voted to use the first $21.6 million to free up money for capital projects and then to save 50 percent of any additional dollars to pad the city’s reserves.

On Tuesday, council members argued for more than three hours largely about how to spend any remaining dollars. Under the plan approved in May, more police officers would be the top priority, fully funded with about $43 million in new revenue.

But Mayor Vincent C. Gray (D) intervened last week, asking the council to place atop the list $32 million in additional funds for the city’s Medicaid providers. In an unexpectedly heated debate Tuesday, the council split over whether to do so. Gray aides and council allies argued that low reimbursement rates have led one managed care organization to threaten to end its contract, shaking the city’s entire public health-care system. Other members argued that the threats were a negotiating tactic, but their attempt to remove the proposed funding narrowly failed.

Members also supported a proposal by council member Jim Graham (D-Ward 1) to top the priority list with a $1.8 million infusion into “Green Teams” and “Clean Teams,” which supplement regular city services in four city wards. Graham argued that the initiatives employ city residents who recently left prison, helping to keep them out of trouble.

But that provision, plus the Medicaid boost and a $12.5 million proposal to fund school nurses, pushed the police hiring and other concerns far down the priority list. Without the new hires, based on current attrition rates, the number of sworn officers could dip below 3,700 by October 2012 — a level Lanier expressed concern about in a hearing this year.

Kristopher Baumann, chairman of the D.C. police union, said Tuesday’s decisions “made the city less safe.”

“I’ve been out to their community meetings. Their constituents repeatedly ask them for more police,” he said. “I do not know how a ward council member is going to be able to say, ‘Yes, we voted for less police in the city.’ ”

Council member Phil Mendelson (D-At Large) spoke out against Tuesday’s changes and voted against final passage of the budget legislation because of them. “To allow the size of the Metropolitan Police Department to shrink is . . . unacceptable in my view,” he said.

A proposal to replace a previously approved tax on non-District municipal bonds with a new income-tax bracket — floated Monday by council member Mary M. Cheh (D-Ward 3) — was not offered for a vote. Rather, Cheh introduced an amendment that would have placed the elimination of the bond tax as a top priority for the anticipated revenue. It failed, 7 to 6.

Council member Jack Evans (D-Ward 2) joined Mendelson in voting against the final bill, explaining that he opposed the new bond tax, the lack of police hiring and “haphazard” spending throughout the budget. “The whole thing was very poorly handled,” he said.