District Mayor Vincent C. Gray is standing behind a proposed 2012 police budget that would bring staffing to a level Police Chief Cathy L. Lanier has called “trouble.”

Under Gray’s budget, the number of officers would likely drop by the end of the next fiscal year from 3,870 to about 3,700 — approximately 100 fewer than Lanier has said the city needs.

“What the mayor has done with a lean budget is make some tough choices,” said Paul Quander, deputy mayor for public safety and Gray’s interim chief of staff. “It is not our desire to have the number dip below 3,800, but that may be a reality.” Gray (D) has submitted his budget to the City Council, which must adopt a spending plan by July.

Public safety is a priority for Gray, Quander said, and Lanier’s budget calls for her to hire 120 additional officers. But the department expects to lose about 270 by the end of next year through retirement and other separations. About 15 officers leave per month.

In a statement this week, Gray said his $470 million police budget provides for an “adequate number of sworn personnel.” The department’s proposed budget is up about $1 million from last year.

But council member Phil Mendelson (D-At Large), head of the Public Safety and Judiciary Committee, said the budget would leave the department underfunded and understaffed.

At a hearing last month, Lanier said: “Once we go below 3,800, we’re going to have trouble.”

Quander said the mayor has asked Lanier to take another look at deployment and identify sworn officers who are doing administrative work who could instead be out on the streets.

In an e-mail Wednesday, Lanier said the budget would require her to be “creative about prioritizing.”

“Reducing sworn staffing will have an impact,” she said. “While we will have fewer sworn members, we are committed to providing the same high level of service to the city — such as maintaining our level of uniformed patrols and solid investigation teams to close cases.”

But with fewer police on the streets, officers would spend their time racing to calls, weakening their ability to patrol neighborhoods, Kristopher Baumann, head of the labor committee of the Fraternal Order of Police, testified at an April 8 hearing about the police budget.

“As our numbers shrink, all of a sudden officers are back in cars, because it’s radio run to radio run,” Baumann testified. “The effects are going to be everywhere.” Via e-mail Wednesday, he declined a request to comment.

Staffing is as low as it has been since 2006. In 2009, there were more than 4,000 officers. If funded, the department has an authorized strength of 4,200 sworn members.

At the April hearing, Lanier said funding cuts caused her to close the police academy to new recruits this year. Personnel is about 93 percent of her budget, she said.

The last class of recruits was in February, when 44 cadets graduated. Today there are none.

Losing officers comes at a difficult time for the department. Although homicides are at about the same level as last year, property crime is on the upswing for the first time in three years, Lanier said.

“If you do the math, you’ll find that hiring just 120 officers means we don’t keep up,” Mendelson said. “If that happens, it will affect deployment. Something will suffer.”

Mendelson said he’s trying to put an extra $7 million in the department’s 2012 budget to push staffing to 3,900. He also hopes to find an additional $800,000 to add to Lanier’s current funding so she can start hiring this summer.

“We have to take money from other programs,” Mendelson said. He declined to say which ones.

But Quander said it is important to look at the city’s entire pot of money during the budget process.

“We have one budget for the District of Columbia,” he said. “It has to take care of all the needs of the city. If you pull from one area, it may leave another area in a precarious situation.”

Staff writer Nikita Stewart contributed to this report.