WASHINGTON — The Supreme Court’s conservative justices signaled Tuesday they may side with Catholic preschools who refused to sign a pledge to welcome students whose parents are transgender or gay.

At issue is whether a state may, without ever naming religion, attach a condition to public money in Colorado’s taxpayer-funded universal preschool program it knows certain faiths cannot accept.

Colorado launched its Universal Preschool Program in 2023, providing 15 hours per week of tuition-free preschool to every 4-year-old in the Centennial State.

The program is open to public, private, and religious schools as long as they sign a nondiscrimination pact agreeing that a child or parent’s sexual orientation or gender identity won’t impact their enrollment.

Justices Samuel Alito, Neil Gorsuch, Brett Kavanaugh and Amy Coney Barrett all pressed Colorado’s conditions, while Justices Sonia Sotomayor, Elena Kagan and Ketanji Brown Jackson warned that the parishes were asking for a special exemption that no secular school enjoys.

Chief Justice John Roberts, who could hold the deciding vote, pressed both sides.

Roberts opened by noting that the court’s last three rulings for religious schools each struck down laws that singled out a religion by name; Colorado’s does not.

“I’m not quite sure how you limit the applicability of your principle,” he told Nicholas Reaves, the lawyer for the parishes, asking whether it would apply to driver’s licenses, employment benefits and Social Security.

“It seems to me that you’re quite anxious to bury Sherbert,” Roberts later told Colorado’s lawyer, Helen Norton, “perhaps as anxious as the other side is to bury Smith.”

The heart of the dispute lies between those two cases. Sherbert v. Verner, decided in 1963, barred the government from denying benefits over a person’s religious practice — unless it could survive strict scrutiny, the highest legal standard the government must meet to defend a law or policy. Employment Division v. Smith, decided in 1990, cut the other way, holding that a law that applies to everyone generally stands, however heavily it falls on a particular creed.

The parishes had also asked the justices to overturn Smith outright, but the court refused to take up that question. Alito, who has urged the court to toss the precedent in the past, said Tuesday he would not argue for overruling it “here today.”

Gorsuch suggested Colorado had found a backdoor around the court’s recent rulings for religious schools.

“The Constitution tends to deal in substances, not in shadows and procedures,” he said.

Kavanaugh noted that Colorado lets participating preschools set enrollment preferences for a range of secular reasons.

“You can have a vegetarian school, but you can’t have a Catholic school,” he said.

Barrett questioned what problem the rule was supposed to solve.

“It’s just hard for me to imagine that this kind of discrimination is a problem in Colorado and that you could be responding to anything else other than the religious schools,” she said.

Sotomayor pressed Reaves to say plainly whether the schools would reject a child “merely because their parents are homosexual.”

“I would say if it’s the sincere religious exercise of the petitioner, then I think it would be permitted,” Reaves answered.

Sotomayor then asked whether the same principle would let a school exclude black children. Reaves said no.

The schools do not automatically reject the children of gay couples, Reaves told the justices, though enrollment might be refused in some cases.

“The principle at issue here is, do you have to treat them better?” Kagan said.

Jackson pressed the DOJ’s lawyer, Sarah Harris, on the same line, arguing there was “no principled basis” to distinguish a religious objection to gay parents from one to black parents. Harris said a racial exclusion would likely fail strict scrutiny.

Norton told the justices that “Colorado welcomes religious preschools” and that the state’s aim was “equal opportunity, not some opportunity.”

The Trump administration sided with the parishes. Harris called the court’s religious liberty precedents a “Swiss cheese doctrinal setup” and urged the justices to restore stricter protections for believers in public benefit programs.

St. Mary Catholic Parish in Littleton, St. Bernadette Catholic Parish in Lakewood, the Archdiocese of Denver and Daniel and Lisa Sheley, Catholic parents who want to use the funding at a parish preschool, sued in 2023 after the state rejected the archdiocese’s request for a religious exemption.

The archdiocese, which runs 34 preschools, wants its schools to be able to admit only families who agree to uphold Catholic beliefs on sex and gender — a policy Colorado says would let them turn away children because of their own or their parents’ sexual orientation or transgender status.

The parishes sued, arguing the requirement violates the First Amendment’s Free Exercise Clause because Colorado grants exceptions to some providers — including for placing children with disabilities — while refusing to accommodate religious schools.

The lower courts rejected the push by the plaintiffs for a permanent injunction against Colorado’s requirement that schools sign the nondiscrimination pact.

Since 2018, Colorado’s LGBT protections have come before the Supreme Court three times on religious or free speech challenges. The state lost all three.

In March, the justices ruled 8-1 that the state’s ban on conversion therapy for minors, as applied ot a Christian counselor’s talk therapy, regulates speech by viewpoint. They sent the case back for stricter review.

In 2023, the high court ruled against Colorado for trying to force a web designer to create websites for same-sex couples.

Perhaps most famously, the court in 2018 backed a baker in Colorado who refused to bake a customized cake for a gay wedding due to his religious beliefs.

Reaves closed by noting that the Sheleys, the Catholic parents in the case, are short $18,000 because of the policy.

A decision in the St. Mary Catholic Parish v. Roy case is expected by the end of June.