Abortion rights supporters expressed relief on Friday after the U.S. Supreme Court preserved access to a widely used abortion pill but warned of a long fight ahead as a legal challenge to the medication continues.

The move by the court to halt new restrictions on the drug set by lower courts was welcome news less than a year after its conservative majority upended U.S. abortion access by overturning the landmark 1973 Roe v. Wade decision that had legalized abortion nationwide.

Abortion providers had been stockpiling the abortion pill mifepristone or planning to switch to a new regimen amid the battle over the legality of a drug used in more than half of U.S. abortions.

Several providers said late on Friday they would pause plans to change their medication abortion protocol in light of the Supreme Court's order.

"It’s the right decision and a huge relief," said Joshua Sharfstein, a public health professor at Johns Hopkins University and a former FDA official. "The alternative would have not only undermined access to reproductive health care, it would have thrown into disarray drug regulation in the United States."

Friday's order will allow mifepristone to remain available with no new restrictions while a court battle that could take months or longer plays out.

The Supreme Court did not rule on the merits of the case, however, meaning that mifepristone could still be restricted or banned at a later stage in the case.

Abortion opponents said on Friday they were confident the court ultimately would rule in favor of the pill's challengers, who contend that the FDA illegally approved mifepristone and then removed critical safeguards on what they call a dangerous drug.

"What the courts will see is a drug that does not cure a disease or alleviate the symptoms of a disease," said Carol Tobias, president of National Right to Life. "It was developed to take the life of an unborn child and always has the potential to harm the mother."