As the Norristown Area School District prepares next year’s budget, Superintendent Christopher Dormer anticipates asking local taxpayers to pay more — again.

The Montgomery County district has repeatedly raised taxes, but with nearly three-quarters of its students considered economically disadvantaged, “we simply can’t generate the kind of revenue that our wealthier suburban neighbors can,” Dormer said.

Adding to the district’s frustrations, an increasing share of its budget is beyond its control — driven in part by rising costs for students attending charter schools, which are paid by local school districts based on enrollment.

Norristown leaders, parents, teachers, and students on Thursday called for immediate changes to a school funding system they described as inequitable and crippling for urban schools in particular.

The district was one of more than a dozen across the state — including Upper Darby and Pottstown — that held news conferences Thursday to draw attention to funding disparities facing districts that are also burdened with increasing costs for charters each year. The conferences, organized by the Pennsylvania League of Urban Schools, were timed to coincide with the anniversary of the Montgomery bus boycotts sparked by Rosa Parks.

“Children of poverty and of color are losing out on opportunities," Dormer said in Norristown, where students of color make up 85% of the district’s enrollment. “We’ve effectively created a segregated school system.”

Their push comes nearly four months after Gov. Tom Wolf announced a plan to overhaul Pennsylvania’s charter school law, calling for greater accountability and transparency for the publicly funded but independently run schools.

» READ MORE: Gov. Tom Wolf pledges to change charter-school policy, says more accountability needed

Since then, the state Department of Education has established fees for charter schools seeking the department’s help in resolving payment disputes with school districts, and moved forward with regulatory changes — including plans to require public audits of charter management companies and better define fiscal and academic standards for charters.

Proposals to change how charter schools are funded require legislative approval, a hurdle for the Democratic governor. Republican lawmakers, who control the legislature, have been supportive of charters, which they view as needed alternatives to traditional public schools, particularly in cities like Philadelphia.

No representatives from Philadelphia participated in Thursday’s coordinated news conferences.

Charter advocates called the campaign “misguided."

“We agree that state lawmakers should reform school funding, especially the gap between wealthy and poor school districts, but taking funding from public charter schools will hurt the families that this organization says it wants to help,” said Ana Meyers, executive director of the Pennsylvania Coalition of Public Charter Schools.

While Pennsylvania changed its school-funding formula several years ago to steer more money toward poor school districts, the changes only apply to a portion of what the state spends on public education. A lawsuit against the state over school funding is pending, highlighting wide disparities between wealthy and poor districts. Lawmakers have not endorsed a redistribution of funding.

» READ MORE: In Pa. school-funding maze, formula for equity elusive

Some Republicans have been considering changes to the state’s charter school system, including cyber charters, which draw students — and dollars — from school districts across Pennsylvania and whose students as a whole perform poorly on tests.

Dormer said Norristown isn’t trying to attack individual charter schools, but is pointing out the costs to districts that are also facing rising pension and special education expenses. Norristown, which has a $160 million budget, sent $9.5 million last year to charters.

None are in Norristown: Some students attend charters outside the district, Dormer said, while a growing number attend cyber charters.

“This is about a flawed system,” he said.