WASHINGTON ― President-elect Donald Trump has repeatedly changed his mind on abortion. He described himself as “very pro-choice” before he decided to run for president. During the campaign, he suggested that states should be able to outlaw abortion, and that women should be punished for having them. At one point, he offered five different positions on abortion in three days.

It’s too soon to say which policies he will support in office. He has run on a pro-life platform, and his vice presidential pick, Indiana Gov. Mike Pence, signed an extreme law in March banning abortions in cases of fetal abnormality. (A federal court blocked that law from taking effect.) With the GOP in control of both chambers of Congress and at least one open seat on the Supreme Court, the effect on abortion rights could be devastating.

The Trump campaign did not respond to a request for comment.

“The pressure is going to be on [Trump] to restrict reproductive freedom, because a lot of the people who put him into office are looking for payback,” said Ilyse Hogue, president of NARAL Pro-Choice America.

The first test, Hogue said, will be Trump’s appointment of a replacement for the late Justice Antonin Scalia. Trump has claimed that if he has the opportunity to put pro-life justices on the U.S. Supreme Court, Roe v. Wade ― the 1973 decision protecting the right to have an abortion until the fetus is viable outside the womb ― will be overturned “automatically.” In reality, when it comes to social issues like abortion rights, there is a solid bloc of four votes on the court in favor of protecting access, as well as a swing vote with Justice Anthony Kennedy. The court reaffirmed a woman’s right to end her pregnancy in a landmark June decision that struck down abortion restrictions in Texas.

But some of the court’s staunchest liberals are getting older ― Justice Ruth Bader Ginsburg is 83 ― and a retirement or a death would give Trump another vacancy to fill. That would give conservatives a 5-4 majority to potentially overturn Roe or otherwise chip away at access to abortion. Some of the most influential abortion cases in recent years have been 5-4 decisions that limited access in some way ― like 1992’s Planned Parenthood v. Casey, which upheld Roe but also let Pennsylvania impose restrictions such as a 24-hour waiting period and parental consent for minors, or 2007’s Gonzales v. Carhart, which upheld a federal law barring a method of late-term abortion. The anti-abortion movement has used restrictions like these to make abortions harder to get without outlawing them completely.

If opponents of Roe were able to attack the decision head-on, the impact would be staggering for women accustomed to having access to safe and legal abortion in the United States. Trump has promised that abortion will “go back to the states,” but in reality, a complex map of state laws, court decisions and other factors would determine who would be permitted to have an abortion and where. The Center for Reproductive Rights estimated in a 2007 report that women in 21 states, including Ohio and Texas, would be at “high risk” of losing access to legal abortion.

And a Trump presidency would finally allow Republicans in Congress to defund Planned Parenthood, which they’ve tried to do eight times since 2011. Planned Parenthood, the largest family planning provider in the country, receives roughly $500 million a year in federal grants to subsidize birth control, pap smears and testing and treatment for sexually transmitted infections for low-income patients. Under Trump, Congress will likely try to end funding for those services, because some of Planned Parenthood’s health centers also perform abortions. (A long-standing federal law, the Hyde Amendment, specifically prevents that funding from being used for abortions, but conservatives still argue that any money going to Planned Parenthood is propping up abortions.)

Anti-abortion advocates have been rejoicing over Trump’s election. “Planned Parenthood has been defeated at the ballot box,” said Lila Rose, the president of Live Action. “It’s critical that we unite to hold Mr. Trump to those pledges to defund Planned Parenthood, to appoint pro-life Supreme Court justices, and to ensure that taxpayers are never forced to fund abortions.”

Matt Bowman, senior counsel at the Alliance Defending Freedom, a conservative legal organization, told HuffPost that his group hopes the future Supreme Court will “keep letting states apply common sense protections for women [and] unborn children.”

Trump has promised to sign a federal ban on abortions after 20 weeks of pregnancy, which is two to four weeks before viability. That ban might or might not include exceptions for health risks to the mother or cases of severe fetal abnormalities, which are the primary reasons women have later-term abortions. (If Trump were to sign such a bill, this could also be used to challenge Roe, since it would be unconstitutional under the court’s previous rulings about the point of viability.)

Trump has also promised to make the Hyde Amendment permanent (it currently needs to be renewed every year). That would have the greatest effect on low-income women, who may not have health insurance or may only be covered by Medicaid. (Hillary Clinton wanted to repeal the amendment.)

Trump’s election doesn’t mean a majority of the country supports these restrictions, Hogue said. Sixty-three percent of voters said they oppose overturning Roe in the most recent Pew poll on the issue. Most Americans also oppose defunding Planned Parenthood.

“If Republicans ram these restrictions through, I think they’re going to pay for it in the midterms,” she said.

The GOP also should not underestimate Planned Parenthood, which tends to thrive when it’s under attack. Cecile Richards, president of the family planning provider, assured supporters in a letter after the election that a Trump administration won’t shut down any of her clinics.

“No matter what else happens, we promise one unshakable commitment,” she said. “THESE. DOORS. STAY. OPEN.”

Kate Sheppard contributed reporting.