Leaders representing most of New Orleans’ public schools have come out in favor of a new per-pupil funding formula for state aid, facing off against a smaller group of the city’s selective-admission magnet schools ahead of a final vote on the new formula scheduled for this week.

The state Board of Elementary and Secondary Education is set to take up a plan Thursday that will shift more dollars toward New Orleans schools that enroll greater numbers of students with disabilities. It will provide less funding for students designated as “gifted and talented.”

Predictably, that formula has pitted the city’s magnet schools, which stand to lose some funding, against most of the open-enrollment schools, which tend to have more students with expensive special needs.

Magnet schools like Lusher Charter School and Lake Forest Charter Elementary School — which plan on taking legal action if the formula is approved — argue that the extra funding for special needs shouldn’t come at the expense of other students. And they are skeptical of official promises that no school will lose more than 2 percent of its funding in a given year.

Most of the city’s open-enrollment charter school leaders signed a letter Monday arguing that the new formula makes sense, given the costs often involved in educating the city’s neediest students.

“We believe this formula appropriately prioritizes scarce resources for the most vulnerable children in our city,” said the letter, signed by more than two dozen school leaders. It added: “This formula still provides appropriate resources for gifted and talented students.”

The dispute may ultimately end up in court. James Brown, an attorney for Lusher who also has been hired by Lake Forest, wrote a letter to local and state education officials threatening a lawsuit if the new formula passes.

Brown said the formula would violate both the Louisiana and U.S. constitutions. He said state law requires BESE to approve one funding formula, known as the Minimum Foundation Program, that applies to all districts, rather than drawing up a separate plan for only one parish. He also said that treating students in New Orleans differently would violate due process and equal protection rights.

Advocates for the new formula say the same MFP formula will still apply to Orleans Parish and that BESE is only stipulating how the local district’s state funding is to be divided among schools.

Another of the city’s selective schools, Ben Franklin High School, held a special board meeting on the issue Tuesday and voted to send a letter asking BESE for a delay until the school can get more information.

Board member Carlos Zervigon said there is still considerable confusion about how the new formula will work, especially for schools that were not privy to meetings of the local task force that negotiated the details.

He said, for instance, that it isn’t clear to Franklin’s finance chief what will be used as the base amount of funding when calculating whether a school’s allocation has dropped by the maximum 2 percent.

“This has been very difficult because we’ve never had a direct channel to the discussions,” he said. “We’ve never received answers.”

A BESE committee is scheduled to vote on the formula Thursday, followed by a full board vote the next day.