(NewsNation) — An Oklahoma school board will vote Tuesday on whether the state will allow the first taxpayer-funded religious charter school in the U.S.

It’s a decision that could ignite a legal battle testing the concept of separation of church and state.

The Statewide Virtual Charter School Board will vote on an application backed by the Roman Catholic Archdiocese of Oklahoma City and the Diocese of Tulsa for the creation of St. Isidore of Seville Catholic Virtual School, planned by its organizers to offer online education for kindergarten through high school initially for 500 students and eventually 1,500.

The board is a state entity that considers applications for charter schools, publicly funded but independently run, that operate virtually in Oklahoma.

Though a small number of charter schools may be affiliated with religious organizations, St. Isidore would be the first to be explicitly religious in its curriculum and operations, The New York Times reported.

The school would cost Oklahoma taxpayers up to $25.7 million over its first five years of operation, its organizers said. The idea for the school came from the Catholic Archdiocese of Oklahoma City. The law school at the University of Notre Dame, a Catholic institution in Indiana, helped with the application.

Any legal fight over St. Isidore could test the scope of the U.S. Constitution’s First Amendment “establishment clause,” which restricts government officials from endorsing any particular religion or promoting religion over nonreligion.

Oklahoma Republican Gov. Kevin Stitt, who supports the school’s application, has argued that excluding religious charter schools is a violation of the First Amendment’s prohibition on religious discrimination, The New York Times reported.

The board’s three voting members all were appointed by Republican state officials.

Supporters and critics of the proposed school predicted a legal fight regardless of the outcome of Tuesday’s vote. Church officials have said they hope the case will reach the U.S. Supreme Court, whose 6-3 conservative majority has taken an expansive view of religious rights including in two rulings since 2020 concerning schools in Maine and Montana.

Brett Farley, executive director of the Catholic Conference of Oklahoma, said St. Isidore is intended primarily to meet the needs of rural families who desire a Catholic education but do not live close to any physical schools.

Farley, whose organization represents the church on public policy issues, said the recent Supreme Court decisions made him optimistic that the justices would eventually allow a publicly-funded Catholic charter school.

The proposal’s critics have warned of the consequences of allowing taxpayer-funded religious schools.

“Americans need to wake up to the reality that religious extremists are coming for our public schools,” said Rachel Laser, president of the advocacy group Americans United for Separation of Church and State.

It remains an open question how the school would balance federal and state non-discrimination rules such as those barring discrimination based on sexual orientation. The school’s stated aim in its application is to hire educators who live by the doctrine of the Catholic Church, which according to the U.S. Conference of Catholic Bishops considers homosexuality a sin.

Farley said he could not answer questions about any hypothetical case of hiring a gay teacher or admitting a gay student, but expressed confidence that the school could “square with state regulations, federal regulations and operate within the protections that precedent has given us.”

“This idea of separation of church and state is not constitutional, it’s not anywhere in the Constitution’s text,” Farley said.

Laser disagreed and said her organization would fight the Catholic church in any court over St. Isidore and any other publicly funded religious school.

“There is an attack being waged on public schools in Oklahoma, and that attack is to convert public schools into religious schools,” Laser said.

Robert Franklin, chairman of the Statewide Virtual Charter School Board, would not reveal how he planned to vote but said that “most all external contacts that have reached out to me are vexed and opposed to the request of the archdiocese’s application.”

Franklin said all three voting board members would have to agree for the school’s application to be approved.