The Virginia state Senate is expected to vote Monday on a measure that would weaken a land-use tool used for decades by local governments to get builders to add roads, parks and other improvements to new home developments.

The bill, which calls for placing restrictions on what local officials can ask for in development negotiations, is one of two measures working its way through the General Assembly. A House version of the bill passed 68-27 last week.

Both measures are generating strong opposition from local officials in Northern Virginia, where development deals have helped shape the character of some of the region’s fastest-growing communities.

Fairfax, Loudoun and Prince William county officials say that changing the legislation would hamper their ability to negotiate for extra amenities from developers that, in the past, have been crucial to community support for new housing in places like Merrifield or Woodbridge. Officials also argue that amending the land-use tool would open them up to lawsuits if builders whose projects were rejected argued that they were denied because of their refusal to agree to “unreasonable” proffer requests.

“For a community to support new development, the community needs to be assured that the development pays for itself,” said Corey A. Stewart, chairman of Prince William County’s board of supervisors. “These new restrictions that the General Assembly is proposing to place on localities make it more and more diffficult for us to say to the community that a development is paying for itself.”

Virginia’s proffer system has been in use since the mid-1970s, when rampant growth in Fairfax County prompted local officials to demand that builders pay to offset the extra traffic and the added burden to local sewers caused by their large-scale developments.

Proffers now include pot sweeteners in development negotiations, where builders offer to pay for new computers in a local school, landscape an athletic field, or simply provide cash to local governments to use for affordable housing or other needs.

J.M. Snell, president of the Home Builders of Virginia trade group, said the system can be akin to extortion for developers anxious to get their projects approved. Some counties have set uniform cash amounts for proffers regardless of a project’s impact to local infrastructure, he said.

“We feel that proffers have gotten out of control,” said Snell, whose group helped craft the legislation. “They’ve grown out of proportion to where now localities have already predetermined proffers, which become demands, which is exactly the opposite of the word ‘proffer.’ ”

Sen. Mark D. Obenshain (R-Rockingham,) who co-sponsored the Senate bill, said the aim of the legislation is to keep local governments from making far-fetched and arbitrary requests.

The bill requires that proffers be limited to offsetting impacts that are directly attributable to new residential developments or new uses for existing developments. Local governments can require developers to offset the impact to off-site public facilities — such as a sewer system — but only if that builder’s new development also benefits from the improvement.

The Senate version of the legislation does not apply to high-density areas, commercial developments or neighborhoods near Metrorail stations.

Obenshain argued that overly demanding proffers can drive up the cost of home construction, which makes it more difficult for developers to sell those properties at lower prices.

“It has the potential to add $60,000 to the bottom line on the cost of these new homes,” he said. “And, it’s making them unaffordable to working families who work in those counties and who want to live close to where they work, contributing to sprawl and pushing people farther and farther out. “

Sharon Bulova, chairman of Fairfax County’s board of supervisors, said the new restrictions may ultimately lead to development projects’ not being approved.

The legislation ignores nuances of land-use decisions, where government planners typically meet with developers and community members multiple times to work through concerns and hammer out compromises, she said.

“Local government does land use,” Bulova said. “The General Assembly doesn’t do land use, and often they don’t understand the land-use process and how it works, and I think that’s what’s happening with this bill.”

In rapidly growing Loudoun County, officials said the proffer reforms would likely force them to raise property taxes to pay for the extra roads and schools needed to keep up with the growth.

“Is it fair for many residents who are already living here ... to shoulder the entire cost of growth and development through their real property taxes, or should those who generate the need for new public facilities pay a fair share of those costs?” Phyllis Randall, chair of the county board of supervisors, said in a letter to General Assembly members.

However, some local groups support the reforms.

Fred Costello, chair of the land use committee for Fairfax County’s Federation of Citizens Associations, argued the current system unfairly favors large developers who are able to pay bigger amounts into local coffers.

“It really is legalized extortion,” he said, advocating for uniform impact fees that charge developers according to the number of homes being built. “Then, a developer would know exactly what he’s going to pay.”