WASHINGTON (AP) -- The Supreme Court will again wade into the fractious issue of abortion this week when it hears arguments over a medication used in the most common way to end a pregnancy, a case with profound implications for millions of women no matter where they live in America and, perhaps, for the race for the White House.

Two years after the Supreme Court overturned Roe v. Wade and cleared the way for bans or severe restrictions on abortion in many Republican-led states, abortion opponents on Tuesday will ask the high court to ratify a ruling from a conservative federal appeals court that would limit access to the medication mifepristone, which was used in nearly two-thirds of all abortions in the United States last year.

That decision to reverse Roe had immediate political consequences, with Democrats making the case that the court had taken away a right that women held for half a century and winning elections as a result. Even conservative-leaning states like Kansas and Ohio voted against abortion restrictions. If the court were to uphold restrictions on medication abortions it could roil the election landscape in races for Congress and the presidency.

By rolling back Food and Drug Administration changes to the use of mifepristone, the ruling would cut off access to the drug through the mail and impose other restrictions, even in states where abortion remains legal. The restrictions would shorten the time when mifepristone can be used in pregnancy, to seven weeks from 10 currently.

Most adults in the U.S., 55%, believe medication abortion pills are very or somewhat safe when taken as directed by a doctor, according to a KFF poll from May 2023, and 65% have "a lot" or "some" confidence in the FDA to ensure that medications sold in the U.S. are safe and effective.

A decision should come by late June. But no matter the outcome, the Supreme Court has not seen its last abortion case. Legal battles are pending over state restrictions, and new federal limits are likely if former President Donald Trump, Republicans' presumptive nominee for 2024, returns to the White House.

Next month, the justices will hear arguments over whether a federal law on emergency treatment at hospitals must include abortions, even in states that have otherwise banned them.

Mifepristone, made by New York-based Danco Laboratories, is one of two drugs, along with misoprostol, used in medication abortions. Their numbers have been rising for years, and they accounted for 63% of the more than 1 million abortions in the U.S. last year, according to an estimate by the Guttmacher Institute, which supports abortion rights. More than 5 million people have used mifepristone since 2000.

Mifepristone is taken first to dilate the cervix and block the hormone progesterone, which is needed to sustain a pregnancy. Misoprostol is taken 24 to 48 hours later, causing the uterus to contract and expel pregnancy tissue.

Health care providers have said that if mifepristone is no longer available or is too hard to obtain, they would switch to using only misoprostol, which is somewhat less effective in ending pregnancies.

Underscoring the importance of the case, the number of medication abortions is rising for several reasons. Taking pills at home to end a pregnancy is less invasive than surgery, more convenient than having to travel to an abortion clinic and more private, allowing women to avoid anti-abortion protesters who picket clinics.

It's becoming even easier to get the two drugs in some states now that CVS and Walgreens have announced pilot programs to dispense the pills at their pharmacies.

For women living in states with abortion bans or restrictions, mail order delivery may be their only practical option, said Julie F. Kay, executive director of the Abortion Coalition for Telemedicine.

The medication is sent by providers in states that have laws meant to shield them from any legal trouble for working with people who live in states that don't permit medication abortions. The pills cost $150 and usually arrive within three to five days, Kay said.

Last year, 85,000 women worked with order-by-mail abortion provider Aid Access to obtain the medication, said Dr. Rebecca Gomperts, the group's founder. Of those, 50,000 live in states with abortion restrictions, she said.

The current case followed closely the Supreme Court decision in June 2022 that overturned the constitutional right to an abortion. That ruling has led to bans on abortion at all stages of pregnancy in 14 states, with some exceptions, and once cardiac activity can be detected, which is around six weeks, in two others.

Abortion opponents filed their challenge to mifepristone the following November and initially won a sweeping ruling six months later from U.S. District Judge Matthew Kacsmaryk, a Trump nominee in Texas, which would have revoked the drug's approval entirely. The 5th U.S. Circuit Court of Appeals left intact the FDA's initial approval of mifepristone. But it would reverse changes regulators made in 2016 and 2021 that eased some conditions for administering the drug.

The Supreme Court put the appeals court's modified ruling on hold, then agreed to hear the case, though Justices Samuel Alito, the author of the decision overturning Roe, and Clarence Thomas would have allowed some restrictions to take effect while the case proceeded.

The doctors and groups that initially wanted mifepristone pulled from the market now say, in their main Supreme Court brief, that those recent changes "jeopardize women's health throughout the nation" and didn't follow the rigorous procedures required by federal law to alter safety restrictions on drugs.

"The Supreme Court's got a chance to decide whether some agencies get a pass in decision making," said Sarah Parshall Perry, a lawyer at the Heritage Foundation who supports the challenge.

Pregnant women who wish to take mifepristone, for example, no longer need an in-person visit with a doctor before getting a prescription, said Erin Hawley, the Alliance Defending Freedom lawyer who is representing the abortion opponents at the Supreme Court.

"Our clients are asking the FDA to put back in place safeguards that were there for nearly 20 years," Hawley told The Associated Press. She is married to Sen. Josh Hawley, R-Mo. Both Hawleys served as law clerks to Chief Justice John Roberts early in their careers.

But the administration said the elimination of doctor visits and the other changes were the product of more than 20 years of experience in regulating mifepristone, including evaluating safety data and studies of thousands of women. Its view is shared by several leading medical organizations, including the American College of Obstetricians and Gynecologists.

Seven former FDA commissioners said in a court filing that the agency exercised special care in its initial approval of mifepristone because it was dealing with an abortion drug. Subsequent changes were "driven by a straightforward and thorough application of the expert scientific review process that Congress entrusted to FDA," they wrote.

Mary Ziegler, a law professor at the University of California at Davis who has written extensively about abortion, said rolling back the FDA rules "would render pretty much all the doses of mifepristone on the market potentially misbranded and mislabeled, which could mean, I think, you know, months of disruption in terms of the drug being available."

More broadly, Ziegler said, the "case has the potential, obviously, to upend how drug approvals function." The prescription drug industry also has weighed in forcefully on the administration's side.

The administration and Danco both make extensive arguments, contested by the other side, that the abortion opponents lack the legal right, or standing, to bring the case.

If the court agrees they're right, it would preserve access for mifepristone without touching on the more politically sensitive issues in the dispute.

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Associated Press writer Linley Sanders contributed to this report.