While it is unclear if the Supreme Court will throw out 45 years of precedent and overturn Roe, the court is more starkly divided along ideological lines than it was in previous years when Roe’s protections were challenged and ultimately upheld. If the court avoids the far-reaching step of actually overturning Roe, it could chip away at the ruling by upholding a series of state restrictions.

“Instead of having the constitutional fight be over if Roe is overturned, you’re actually going to see constitutional fights continue and multiply in different states,” said Mary Ziegler, a law professor at Florida State University and the author of “Beyond Abortion: Roe v. Wade and the Battle for Privacy.” Advocates are looking to codify protections in state constitutions by pushing ballot initiatives, urging legislatures to pass constitutional amendments, and asking state supreme courts to reinterpret constitutional provisions.

For decades, supporters of abortion rights could look to a bulwark at the federal level to preserve the core of Roe at key moments: Justice Anthony M. Kennedy, the Supreme Court’s swing vote, whom Justice Kavanaugh replaced this month. While Justice Kennedy could be an unpredictable vote on abortion rights, in crucial cases he frequently joined the court’s liberals in reaffirming the principles underpinning Roe.

“As long as Kennedy was on the court, I think it’s fair to say that the tendency was to rely on federal courts to protect those rights,” said Maya Manian, a professor at the University of San Francisco School of Law.

“Now that the writing is on the wall,” she said, “you’ve got to turn to other avenues, which in our federal system would be the states.”

That state-by-state approach has long been employed by opponents of abortion rights, particularly in the aftermath of the 2010 elections, when Tea Party insurgents swept into office, said David S. Cohen, a law professor at Drexel University. This year alone, state legislatures have passed a series of restrictive measures, including one in Kentucky that would curb an abortion procedure as early as 11 weeks into a pregnancy. Most of the measures have been challenged in court.

Abortion opponents have also sought to enact new limits through ballot initiatives. Next month, voters in three states will vote on restrictive measures, including a proposed constitutional amendment in Alabama that would “recognize and support the sanctity of unborn life and the rights of unborn children.”