Montgomery County lawmakers are set to vote Tuesday on highly contentious piece of legislation aimed at protecting janitors and cafeteria workers from losing their jobs when a contract ends.

The bill would require places like private schools, hospitals, apartment buildings, museums and office buildings that contract out services such as building maintenance or food preparation to keep the service employees for an additional 90 days if they dismiss the contractor. If a new contractor replaces an old one, the new contractor must hire the employees. If the building decides to perform the services in-house, the building manager must hire the employees for the 90-day period.

With five co-sponsors on the County Council, the bill is the direct result of lobbying by the Service Employees International Union.

The legislation's advocates argue that the measure is a necessary protection for low-income workers who are often subject to the whims of an unstable market.

"If a new contract takes effect, they should have a chance to find work -- alternative work -- or to show the new contractor that they can perform the work," said John Berg, a retired economist who lives in Silver Spring. "It just seemed to me that that's the way workers should be treated."

But the bill gives special treatment to private-sector workers, a perk that is not available to the government's employees, said Gino Renne, president of the Municipal and County Government Employees Organization, which represents county government employees. Though Renne emphasized that he supports the bill's premise, he said he would like to see it expanded to cover public employees.

He pointed to a group of technology services workers who lost their contract with the county in a round of budget slashing. "The County Council showed no sensitivity, interest whatsoever toward the impact on those workers, and they were all displaced."

The business community has lined up to oppose the bill.

"I just don't think it's right for the government to be involved with who I have to hire," said Henry Tripp, president of Gardener's General Contractors, a Frederick company that provides some of the kinds of contracts covered by the bill. "There's a reason they're getting replaced, anyways. They're probably not doing a good job, or it's costing too much."

Bethesda real estate agent Jane Fairweather said she worries the bill will drive business away, which means fewer customers for her.

"It's a bill that makes Maryland -- Montgomery County in particular -- look business-punitive, and we already lose on so many levels to Virginia. So many levels," she said. "It's very, very hard to compete with that side of the river, and this just makes it worse."