A challenge at the US Supreme Court by Catholic groups to a Colorado law barring anti-LGBT discrimination at publicly funded preschools is testing whether conservative religious interests can extend their winning streak in major cases at the nation's top judicial body.

The court, whose 6-3 conservative majority has taken a broad view of religious liberty, will hear arguments on Tuesday over a bid by the Archdiocese of Denver and other Catholic entities for an exemption from a Colorado preschool funding program's nondiscrimination requirement. Republican President Donald Trump's administration is backing the Catholic groups.

Officials in Democratic-governed Colorado have accused the Catholic preschools of seeking legal permission to discriminate against 4-year-olds and their families while receiving taxpayer dollars.

The case will give the court an opportunity to further expand the sweep of a provision of the US Constitution's First Amendment called the Free Exercise Clause, which protects the right to practice religion without government interference.

It also represents the latest clash between religious rights and LGBT protections at the court, where conservative religious interests in recent years have prevailed in a series of such disputes.

"These cases reflect a very conservative court, following the conservative agenda on the religion clauses and LGBT issues," Erwin Chemerinsky, dean of the University of California, Berkeley Law School, said of the recent rulings.

The First Amendment religion provisions also include the Establishment Clause, which restricts the government from establishing or endorsing any particular religion, or promoting religion over nonreligion. This provision underpins the concept of separation of church and state.

Colorado children in 2023 became eligible under state law for 15 hours per week of state-funded preschool before entering kindergarten. Participating preschools may be public or private, secular or religious. But in each case, under the law, schools must give all children "equal opportunity" to enroll, regardless of the sexual orientation or gender identity of the students or parents.

The Archdiocese of Denver along with other Catholic entities and a Colorado family sued as the state's universal preschool initiative was ramping up. They argued that the program's anti-discrimination mandate burdened their religious exercise.

The archdiocese oversees 34 Catholic preschools, according to court papers. Its policy is to admit students only from families who support Catholic beliefs, including on same-sex relationships and gender identity.

The Catholic Church recognizes marriage as a union only between a man and a woman, not same-sex couples, and opposes transgender self-identification. The Catholic Church's catechism, a compendium of its teachings, also states that "homosexual acts are intrinsically disordered" and that "under no circumstances can they be approved." A Colorado-based federal judge in 2024 upheld the state program's protections for LGBT people. The Denver-based 10th US Circuit Court of Appeals affirmed that ruling last year, prompting the current appeal to the Supreme Court.

Citing the Supreme Court's 2015 ruling that legalized gay marriage nationwide, lawyers for the Catholic preschools told the justices in a filing that the court in that decision promised "that religious groups would be protected when they dissent from secular orthodoxies about marriage and sexuality." "The Free Exercise Clause simply cannot do that important work — which this court has described as 'at the heart of our pluralistic society' — if it can be so easily evaded," they wrote.

The challengers are represented by the Becket Fund for Religious Liberty, a conservative legal group whose website touts its "unparalleled, undefeated record" in 13 cases before the Supreme Court, 6 of which were unanimous decisions.

Colorado has argued that its equal-opportunity requirements do not intrude on the Free Exercise Clause because they are neutral and apply generally to participating groups.

Colorado bases its argument on a 1990 Supreme Court precedent in a case called Employment Division v. Smith that upheld "generally applicable" laws even if they curb religious freedom. Despite being authored by the staunchly conservative late Justice Antonin Scalia, that ruling has long been in the crosshairs of conservative litigants.

The Supreme Court, in agreeing to hear the Colorado case, formally declined to consider overruling Smith. But a group of constitutional scholars who back Colorado cautioned the justices that embracing the broadest argument presented by the Catholic groups would gut the precedent.

Doing so, they argued in a filing, would usher in a "most-favored nation" rule for religion, meaning that exceptions granted for secular activities would make it difficult for states to deny comparable exceptions for religious activities.

"The original public meaning of the (Free Exercise) Clause is that it forbids laws targeting religion as such, not that it affirmatively requires religious exemptions from laws that the state permissibly enacts," the scholars wrote in their brief.

A core disagreement in the case is whether Colorado discriminated against the Catholic preschools by refusing to exempt them from the equal-opportunity requirement, while at the same time allowing preschools to prioritize the enrollment of low-income and disabled students.

The court's thinking on this question may be guided by its recent decisions that expanded access by religious schools to public money in response to policies that, in the view of the justices, had unlawfully excluded religious institutions.

In 2022, the court ruled in favor of two Christian families in their challenge to a Maine program that provided state-funded tuition assistance that had excluded private religious schools. In 2020, it endorsed Montana tax credits that helped pay for students to attend private religious schools, ruling in favor of three mothers of Christian school students.

Those decisions followed the court's 2017 ruling in favor of Trinity Lutheran Church of Columbia, Missouri, that declared that churches and other religious entities cannot be flatly denied public money based on their religious status — even in states whose constitutions explicitly ban such funding.

Advocacy groups backing Colorado, including the ACLU and Americans United for Separation of Church and State, told the justices in a filing that the state's preschool funding program is neutral toward religion.

Siding with the Catholic groups, they argued, would force the government "to provide taxpayer dollars – and the state's imprimatur – to beneficiaries whose conduct undercuts state policy goals, including equality goals." In several recent cases the Supreme Court has sided with conservative religious litigants over competing LGBT interests.

The court in March rejected a Colorado law that barred psychotherapists from using "conversion" talk therapy intended to change an LGBT minor's sexual orientation or gender identity, siding with a Christian licensed counselor in casting the ban as an intrusion on First Amendment free speech rights.

The court last year sided with Christian and Muslim parents in Maryland who sued to keep their elementary school children out of certain classes when storybooks with LGBT characters are read.

In another blow to LGBT rights, the court ruled in 2023 that the First Amendment right to free speech allows certain businesses to refuse to provide services for same-sex weddings. And in 2018, it sided with a Colorado baker who refused based on his Christian beliefs to have his shop make a wedding cake for a gay couple, based on the Free Exercise Clause.

The court's liberal justices have raised the alarm in recent cases, arguing that the conservative majority is undermining church-state separation as envisioned in the Establishment Clause.

Dissenting in the 2022 case from Maine, liberal Justice Sonia Sotomayor wrote, "Today, the court leads us to a place where separation of church and state becomes a constitutional violation."