NASHVILLE (AP) — A Tennessee judge on Friday agreed to allow school choice advocates to intervene in a lawsuit challenging the legality of the state's school voucher program.

That means the Liberty Justice Center, the Institute for Justice and the Beacon Center of Tennessee will all have a chance to defend the much-debated voucher program as the case moves through the courts.

Earlier this year, Tennessee's largest communities — Nashville and Memphis — filed a complaint alleging the state's voucher program is illegal under the state constitution's "home rule." They claim Republican lawmakers did not receive local consent when drawing legislation affecting local communities.

School choice advocates are now pushing back, arguing that it's important to represent qualifying families who want to sign up for the voucher program next school year.

"We're confident this is going to be an argument that will prevail and educational liberty will be protected and that the school choice program is constitutional," Arif Panju, a managing attorney for the Institute for Justice. "We're willing to litigate this all the way up to the Tennessee Supreme Court if necessary."

Tennessee's voucher program is scheduled to go into effect this summer. However, the plaintiffs hope to stop the program from being implemented.

Under the program — which Gov. Bill Lee signed into law in 2019 — the state would allow eligible families to use tax dollars on private education starting in the 2020-21 school year. Otherwise known as education savings account, families would get up to $7,300 in state education money each year that could be spent on preapproved private school tuition and other expenses.

The voucher program would only apply to Nashville and Memphis, the areas with the lowest performing schools and regions with Democratic political strongholds.

Davidson County Chancellor Anne C. Martin urged attorneys on both sides of the case to work together as much as possible, noting that the 2020-21 school year was only a few months away.

"I'm somewhat concerned about the tight timeline of the school year ... but I'm glad that we're thinking towards getting to the meat of these issues quickly," Martin said.

Friday's hearing did not apply to the separate lawsuit that was recently filed targeting the Tennessee voucher program.

In that case, the American Civil Liberties Union of Tennessee, the Southern Law Poverty Center and the Education Law Center have filed a claim echoing similar arguments raised by Nashville and Memphis.

However, the civil rights groups — who represent parents opposed to education savings accounts — also said the voucher law must be spiked because tax dollars will be spent on private schools that could discriminate against certain students.

Currently, the voucher law requires participating private schools to agree they won't discriminate against students on the basis of race, color or national origin. Yet there is no such requirement on the basis of sex, religion or disability.

Christopher Wood, a private Nashville attorney working on the second lawsuit, says it's a possibility the two lawsuits could be consolidated but warned it's still too early to speculate if that will happen.

"We obviously have the same kind of goal as the plaintiffs in this case and if there's a more efficient way to achieve that in a quicker way that's all the better," Wood said.

Panju said his group and others planned on intervening in the second case later Friday.