The drug will remain widely available as the justices extended their deadline to Friday on whether to uphold the F.D.A.’s approval of the pill.
WASHINGTON — The Supreme Court on Wednesday extended for two days a pause on a lower-court ruling that had sought to limit access to the abortion pill mifepristone, ensuring that the drug would continue to remain widely available for now.
In a brief order, Justice Samuel A. Alito Jr. announced that the pause would lapse on Friday at midnight, giving the court more time to consider the case, though it could act before then.
That the court did not meet an earlier deadline suggests there may be disagreement among the justices in its first major case about abortion access since a conservative majority in June upended the constitutional right to an abortion. It could also indicate there may be a dissent in the case.
At issue is a ruling by Judge Matthew J. Kacsmaryk of the Northern District of Texas, who in recent weeks had declared invalid the Food and Drug Administration’s approval of mifepristone, part of the most commonly used method for ending pregnancies in the United States.
The court’s order slows what has been a muddled and fast-moving landscape for mifepristone, marked by conflicting Federal District Court decisions and an appeals panel ruling that further complicated the drug’s legal status.
After the Supreme Court overturned Roe v. Wade, the landmark 1973 case, in June, political and legal battles have centered on medications used for abortions. In some conservative states, lawmakers have targeted pills.
Medication abortion, a two-drug regimen, is typically used in the first 12 weeks of pregnancy. The first drug, mifepristone, blocks progesterone, a hormone that allows a pregnancy to develop, and the second, misoprostol, taken one or two days later, prompts contractions and helps the uterus expel its contents.
The dispute started in Texas in November, when an umbrella group of medical organizations and a few doctors who oppose abortion sued the F.D.A., challenging its approval of the pill more than two decades ago.
In their suit, the anti-abortion groups claimed that the F.D.A. did not follow proper protocols when it approved the drug in 2000. The groups said that the agency had also ignored dangers of the drug in the years since.
The F.D.A., vigorously countering those claims, has said that the drug was properly approved more than 20 years ago and that it is very safe. It has cited years of scientific studies that show that serious complications are rare and that less than 1 percent of patients need hospitalization.
The lawsuit was filed in the Amarillo division of the U.S. District Court for the Northern District of Texas, where a single federal judge, Judge Kacsmaryk, an appointee of President Donald J. Trump, hears cases.
Judge Kacsmaryk, a longtime opponent of abortion, is a former lawyer for First Liberty Institute, a legal group focused on religious liberty cases that has long backed conservative causes.
This month, Judge Kacsmaryk announced a preliminary ruling that invalidated the F.D.A.’s approval of the drug. But the judge said that the agency had a week to seek emergency relief before his ruling would take effect.
Judge Kacsmaryk suffused his ruling with the language of the anti-abortion movement, referring to abortion providers as “abortionists” and a fetus or embryo as an “unborn human” or “unborn child.” He appeared to agree with virtually all of the claims made by the anti-abortion groups.
Less than an hour later, another federal judge, Thomas O. Rice, who was appointed by President Barack Obama, issued a contradictory ruling in Washington State in a different lawsuit. Judge Rice blocked the F.D.A. from limiting the availability of mifepristone in much of the country.
The Washington State lawsuit, filed by Democratic attorneys general in 17 states and the District of Columbia, is a direct challenge to the Texas case.
The Biden administration immediately appealed the ruling by the federal judge in Texas, and a divided three-judge panel of the U.S. Court of Appeals for the Fifth Circuit, based in New Orleans, announced that mifepristone could remain legal and available while the lawsuit makes its way through the courts.
The panel rejected Judge Kacsmaryk’s finding that the F.D.A.’s approval of mifepristone was not valid. At the same time, the judges blocked more recent steps by the F.D.A. to make the drug more easily available, including permissions to send the pills by mail.
The next day, Judge Rice reaffirmed his ruling, ordering the F.D.A. to maintain the status quo in the 18 jurisdictions, sowing further confusion about the availability of the abortion pill.
The dueling orders all but guaranteed that the case would go to the Supreme Court.
The Biden administration, seeking emergency relief, asked the justices to pause the lower-court ruling that sought to limit access to the pill. In its brief, the government argued that the decision had sweeping consequences, not only for abortion pill access but also for the broader pharmaceutical industry.
If the ruling went into effect, the government said, it would “upend the regulatory regime for mifepristone.”
In their brief, the anti-abortion groups that filed the suit contended that “for nearly a quarter-century,” the F.D.A. and the drug’s manufacturer, Danco Laboratories, had “brazenly flouted the law and applicable regulations, disregarded holes and red flags in their own safety data, intentionally evaded judicial review and continually placed politics above women’s health.”
The government and Danco emphasized how consequential the orders from the lower courts would be, if they were to stand.
“Absent a stay, the lower courts’ unprecedented nationwide orders would scramble the regulatory regime governing a drug that F.D.A. determined was safe and effective under the approved conditions and that has been used by more than five million American women over the last two decades,” Solicitor General Elizabeth B. Prelogar, representing the F.D.A., wrote in a second brief.
Danco Laboratories said in its reply that the plaintiffs’ argument would “radically rework standing jurisprudence.”
“If this litigation involved any other drug, there would be no debate that a group of doctors who  do not prescribe it and  rely on a statistical possibility of encountering a patient in need of follow-up care would be found to lack standing,” the brief said.
Adam Liptak and Pam Belluck contributed reporting.