After years of belt-tightening, Montgomery County Executive Isiah Leggett (D) proposed an operating budget Thursday that would beef up public safety and library services while keeping funding for many other programs and services at current levels.

But with state budget deliberations up in the air, county officials are worried that the proposal might be unrealistic and that they will be forced to make another round of painful cuts.

Under Leggett’s $4.6 billion proposal for fiscal 2013, the county would add 43 police officers and give a 10 percent boost to county libraries, which have seen funding drop by nearly 30 percent since fiscal 2009. Meanwhile, Leggett is proposing what would amount to an average $4 increase in homeowners’ annual property tax bills.

Leggett also proposes to keep an unpopular tax increase on energy use that is sheduled to expire in June. He also wants to slash by nearly 25 percent an expected $147 million payment to retiree health benefits, which have been underfunded in recent years. Officials say the two measures would give Montgomery about $150 million in breathing room.

The County Council has final say over the operating budget and is scheduled to act on it in May.

Leggett’s 2013 proposal calls for $199 million in additional spending, an increase largely driven by a boost in funding for public safety and schools. In the previous five fiscal years, the county made $2.5 billion in cuts in projected spending to balance its budget. Spending on most county programs and services peaked in fiscal 2009, although school funding increased from year to year and the proposed 2013 public safety budget would exceed its 2009 level.

Some other programs would see small increases in fiscal 2013, which begins July 1. At $267 million, the budget for health and human services would be $6 million more than in fiscal 2012 but $27 million less than in fiscal 2009.

County officials said the outcome of the General Assembly’s debate over school funding could have a significant effect on the local budget. The worst-case scenario would have county officials plugging a hole of about $200 million. Leggett said he would be more inclined to make cuts than raise taxes.

It appears that some of the more controversial measures under consideration in Annapolis would not affect the county’s fiscal 2013 budget, including proposals to shift some of the rising cost of teacher pensions to the counties while making it harder for counties to cut classroom spending.

Democratic lawmakers would also give the state the power to seize county tax revenue and hand it directly to school boards as a way to ensure that counties maintain what are among the nation’s highest levels of per-pupil spending.

The final numbers won’t be known until the state budget is finalized, which the legislature is supposed to have done by April 2. In late April, Leggett is expected to unveil a list of revisions to this week’s proposal.

Council officials say the revisions, which are made every year, are usually manageable. But in 2010, when a $200 million hole opened in the fiscal 2011 budget, Leggett proposed a midyear revision, including a controversial ambulance fee that later was struck down by referendum vote.

Last week, County Council member Nancy Floreen (D-At Large) said that given the situation in Annapolis, she and other council members would not be able to commit to anything in Leggett’s proposal at this point. She described the county executive’s proposal as “academic.”

Leggett disagreed with Floreen’s characterization, but he acknowledged that there could be a “huge hill to climb.” The state debate “will have enough of an impact, to put it mildly,” he said.

In most years, only state legislation that has been approved is taken into consideration when the council prepares its budget. With so much still up in the air in Annapolis, county officials have had to make many assumptions.

“I don’t recall so much at such a material impact to the county being unsettled at this point,” said Joseph F. Beach, the county’s finance director and former budget director.