A group of students holds heart balloons to show support for "heartbeat" bills during the March for Life, the world's largest annual anti-abortion demonstration, in D.C. on Jan. 19, 2018. (Carolyn Van Houten/The Washington Post)

For decades, established antiabortion leaders pushed for incremental steps toward chipping away at abortion through state laws, such as making it harder for women to access abortion providers or requiring them to view ultrasounds. But many activists are pressing for a more aggressive strategy now that, they say, the Supreme Court could be on their side.

Lawmakers in several GOP-led legislatures have pushed “heartbeat bills” in hopes of getting the Supreme Court — including President Trump appointees Neil M. Gorsuch and Brett M. Kavanaugh — to pick up a case that would challenge Roe v. Wade.

The bills have been proposed in at least 11 states and would ban almost all abortions after a fetal heartbeat can be detected, usually around six to eight weeks into pregnancy. Heartbeat bills were signed into law in Ohio and Mississippi.

In their Roe decision in 1973, the justices said states may not restrict abortion before the fetus is viable, usually around 23 or 24 weeks of pregnancy, so lower courts are expected to declare “heartbeat laws” unconstitutional.

The strategy has been decried as reckless by some who fear that the attempts could backfire. In Tennessee, Catholic bishops last month opposed a heartbeat measure, warning that the state could have to pay hundreds of thousands of dollars in attorney fees if Planned Parenthood sued and won. The bill, also opposed by antiabortion group Tennessee Right to Life, is awaiting action in the state Senate. Bishops in states such as Florida and Georgia, on the other hand, support their states’ heartbeat measures.

“Impatience and optimism have changed the rules of the game since Trump was elected,” said Mary Ziegler, a professor at Florida State College of Law who has written on abortion. “Republicans want something that will survive in the courts and show their purity on the issue.”

Clarke Forsythe, senior counsel for Americans United for Life, a Washington-based nonprofit that writes model legislation for state lawmakers opposing abortion, called the heartbeat bills well-intended but misguided.

“The chance of enforcement for any of these laws is not very good,” he said. “The obstacles are substantial.”

Shortly after a similar bill was signed into law in Kentucky this month, a federal judge temporarily blocked the measure from taking effect. A federal judge also struck down an Iowa heartbeat bill in January after it was passed last year.

In a surprise move earlier this year, Chief Justice John G. Roberts Jr. joined with the Supreme Court’s liberals to block a Louisiana law that would have restricted abortion access. In 2016, the justices struck down Texas abortion clinic restrictions, and in 2007, the court upheld the federal ban on partial-birth abortion; after the decision, more states began to pass abortion regulations.

Forsythe believes there’s no sign that the court is looking to hear cases on early-trimester abortions. In 2016, the Supreme Court declined to hear cases where lower courts blocked first-trimester prohibitions from Arkansas and North Dakota.

Forsythe’s group recommends pursuing laws that reduce government support for abortion providers and create pregnancy discrimination protections.

“You can do that with legislation that can be passed, approved and enforced in the immediate future,” he said.

The U.S. Conference of Catholic Bishops in 2011 backed a U.S. congressional proposal that would require abortion practitioners to make the fetal heartbeat audible and visible to pregnant women seeking an abortion. The proposal never passed the House. Now, the conference of bishops’ spokesman Judy Keane said, it defers to bishops in each state to decide their own strategies, which have varied across the country.

Catholic bishops in Ohio, who declined to support a heartbeat measure in 2011 that was blocked in the state Senate, came out in favor of a new heartbeat bill that passed the Ohio legislature and was signed by the governor Thursday.

Janet Porter, president of Faith2Action, which describes itself as a network of pro-family groups, is credited with crafting Ohio’s legislation in 2011 that has become so popular across the nation this year. She was previously legislative director for Ohio’s Right to Life chapter, one of the most prominent antiabortion groups in the nation, but she said the incremental strategy they were pursuing wasn’t working. She said her new effort is religiously motivated.

“God gave me the idea, and I’ve been pursuing it ever since,” she said.

Elizabeth Nash, senior state issue manager at Guttmacher Institute, a nonprofit research group that supports abortion rights, said most abortion opponents have traditionally focused on incremental strategies, such as making it harder to access abortion through waiting periods and counseling requirements or making it harder for the abortion clinics to stay open. Abortion opponents have been very successful in recent years at passing legislation at the state level restricting abortion.

With the shift in the Supreme Court, she said, abortion opponents see a real opportunity to ban abortion.

“We know the court has shifted to the conservative side,” she said. “The anticipation is that the court will be accepting some kind of abortion case. We don’t know what that case will necessarily be.”

Observers say there are four justices who could cast votes to limit constitutional protections in favor of abortion and four who would vote to uphold such protections, with Roberts serving as a possible swing vote. However, if someone left the bench because of death or another circumstance, Trump would be expected to nominate an antiabortion justice.

James Bopp Jr., an attorney based in Indiana who is general counsel to National Right to Life but did not speak for the organization, considers the heartbeat bills counterproductive. The Supreme Court, he said, will likely consider cases that could eventually limit or overturn Roe v. Wade, but it won’t happen overnight.

“Legislators will use it to say, see how pro-life I am,” he said. “It’s a completely futile effort that accomplishes nothing.”

Many abortion opponents have been eyeing legislation in Virginia and New York that seeks to expand access to late-in-pregnancy abortions.

According to a 2018 Gallup poll, 6 in 10 Americans say abortion “should generally be legal” during the first three months of pregnancy. Support for abortion drops off during the second three months (28 percent) and during the last three months (13 percent).

Support for abortion varies depending on the circumstances, such as whether the life of the mother is endangered. Of those polled, 45 percent say abortion should be legal for “any reason” in the first trimester compared with 20 percent who said this about the third trimester.

Scott Clement contributed to this report.