The Supreme Court is keeping pandemic-era limits on immigration in place indefinitely, dashing hopes of immigration advocates who had been anticipating their end this week.

In a ruling Tuesday, the Supreme Court extended a temporary stay that Chief Justice John Roberts issued last week. Under the court’s order, the case will be argued in February and the stay will be maintained until the justices decide the case.

The limits were put in place under then-President Donald Trump at the beginning of the pandemic. Under the restrictions, officials have expelled asylum-seekers inside the United States 2.5 million times and turned away most people who requested asylum at the border on grounds of preventing the spread of COVID-19. The restrictions are often referred to as Title 42 in reference to a 1944 public health law.

Immigration advocates sued to end the use of Title 42. They said the policy goes against American and international obligations to people fleeing to the U.S. to escape persecution. They’ve also argued that the policy is outdated as coronavirus treatments improve.

A federal judge sided with them in November and set a Dec. 21 deadline to end the policy. Conservative-leaning states appealed to the Supreme Court, warning that an increase in migration would take a toll on public services and cause an “unprecedented calamity” that they said the federal government had no plan to deal with.

Roberts, who handles emergency matters that come from federal courts in the nation’s capital, issued a stay to give the court time to more fully consider both sides’ arguments.

The federal government asked the Supreme Court to reject the states’ effort while also acknowledging that ending the restrictions abruptly would likely lead to “disruption and a temporary increase in unlawful border crossings.”

The Supreme Court’s decision comes as thousands of migrants have gathered on the Mexican side of the border, filling shelters and worrying advocates who are scrambling to figure out how to care for them.

The precise issue before the court is a complicated, largely procedural question of whether the states should be allowed to intervene in the lawsuit, which had pitted advocates for the migrants against the federal government. A similar group of states won a lower court order in a different court district preventing the end of the restrictions after the Centers for Disease Control and Prevention announced in April that it was ending use of the policy.

Until the judge’s November order in the advocates’ lawsuit, the states had not sought to take part in that case. But they say that the administration has essentially abandoned its defense of the Title 42 policy and they should be able to step in. The administration has appealed the ruling, though it has not tried to keep Title 42 in place while the legal case plays out.