WASHINGTON — The Supreme Court appeared divided in its first major abortion case of the Trump era, leaving Chief Justice John Roberts as the likely deciding vote.

Roberts did not say enough to tip his hand in an hour of spirited arguments at the high court Wednesday.

The court’s election-year look at a Louisiana dispute could reveal how willing the more conservative court is to roll back abortion rights.

A decision should come by late June.

The outcome could have huge consequences at a time when several states have passed laws, being challenged in the courts, that would ban abortions after a fetal heartbeat is detected, as early as six weeks.

Abortion-rights protesters filled the sidewalk in front of the court Wednesday morning. A smaller group of anti-abortion demonstrators stood across the street, some blowing shofars, rams’ horns used in Jewish services, to try to drown out the other side’s speakers.

The justices are weighing a Louisiana law requiring doctors who perform abortions to have admitting privileges at a nearby hospital. A federal judge found that just one of Louisiana’s three abortion clinics would remain open if the law is allowed to take effect. The federal appeals court in New Orleans, though, upheld the law, setting up the Supreme Court case.

Justice Elena Kagan, reflecting the view of her liberal colleagues, noted that a clinic in Shreveport reported transferring just four patients to a hospital out of roughly 70,000 it has treated over 23 years. “I don’t know a medical procedure where it’s lower than that,” Kagan said,

Justice Samuel Alito said the clinic had once had its license suspended, in 2010.

Perhaps the biggest question is whether the court will overrule a 2016 decision in which it struck down a similar law in Texas. Since then, Donald Trump was elected president and he appointed two justices, Neil Gorsuch and Brett Kavanaugh, who have shifted the court to the right. Even with those two additions to the court, Roberts almost certainly holds the deciding vote.

When the justices temporarily blocked the Louisiana law from taking effect a year ago, Roberts joined the court’s four liberal justices to put it on hold. Kavanaugh and Gorsuch were among the four conservatives who would have allowed the law to take effect.

Those preliminary votes do not bind the justices when they undertake a thorough review of an issue, but they often signal how a case will come out.

In more than 14 years as chief justice, Roberts has generally voted to uphold abortion restrictions, including in the Texas case four years ago.

It is for now unclear whether Roberts’ outlook on the Louisiana case has been affected by his new role as the court’s swing justice since Justice Anthony Kennedy’s retirement, his concern about the court being perceived as a partisan institution and his respect for a prior decision of the court, even one he disagreed with.

The chief justice asked an intriguing question about precedent Tuesday, wondering whether a 10-year-old decision would help determine the outcome of a case about the Consumer Financial Protection Bureau. “Do you think that recent precedent should have a binding effect on how the court addresses this case?” Roberts asked.

Louisiana, the Trump administration and anti-abortion groups have all firmly answered that question with a resounding “No.”

Louisiana Solicitor General Elizabeth Murrill told the justices that the Louisiana and Texas laws are not identical. “The laws are different, the facts are different, the regulatory structures are different,” Murrill said.

The Trump administration also argued in court papers that the high court could overrule the Texas case if necessary.

Julie Rikelman, the Center for Reproductive Rights lawyer who argued the case on behalf of the Shreveport clinic, said a trial judge found that abortions in Louisiana are safe and that the law provided no health benefits to women, just as the Supreme Court ruled in the Texas case.

“This case is about respect for the court’s precedent,” Rikelman said.

The court also has agreed to review whether abortion providers have the right to go into court to represent the interests of women seeking abortions. A ruling in favor of the state’s argument that the providers lack the right to sue in these circumstances, known as third-party standing, would be a devastating blow to abortion-rights advocates since doctors and clinics, not individual women who want abortions, file most challenges to abortion restrictions.

But apart from Alito, the justices did not seem especially interested in resolving the case on the standing issue.