When Donald J. Trump ran for president in 2016, the leaders of the anti-abortion movement extracted a series of promises from him in exchange for backing his nomination.

They demanded Supreme Court justices who would overturn Roe v. Wade. They insisted that he defund Planned Parenthood. They pushed for a vice president who was a champion of their cause. And each time, he said yes.

But that was then.

With Roe v. Wade left on the “ash heap of history,” as anti-abortion leaders are fond of saying, they find themselves no longer calling the shots. Their movement remains mighty in Republican-controlled statehouses and with conservative courts, but it is weaker nationally than it has been in years. Many Republican strategists and candidates see their cause, even the decades-old term “pro-life,” as politically toxic. And on Monday, their biggest champion, the man whom they call the “most pro-life president in history,” chose politics over their principles — and launched a series of vitriolic attacks on some of their top leaders.

With his clearest statement yet on the future of abortion rights since the fall of Roe in 2022, Mr. Trump laid bare how faulty a messenger he had always been for the anti-abortion cause. When he first flirted with a presidential run in 1999, Mr. Trump was clear about his position on abortion: “I’m very pro-choice,” he said. He reversed that stance a dozen years later: “Just very briefly, I’m pro-life,” he told attendees at the Conservative Political Action Conference in 2011.

His support shifted again after the Supreme Court’s decision. While he bragged about appointing three of the justices who overturned Roe, he blamed the movement for Republican losses in the midterm elections. He mused aloud about the idea of a federal ban, but refused to give it the kind of ringing endorsement anti-abortion leaders wanted.

In his four-minute video statement on Monday, Mr. Trump said that states and their voters should decide abortion policies for themselves, in language that sounded like a free-for-all to the staunchest abortion opponents. He backed access to fertility treatments such as I.V.F., and supported exceptions to abortion bans in cases of rape, incest and the life of the mother.

His remarks were low on specifics. Mr. Trump skirted the question of whether he would back a federal abortion ban if legislation came to him as president. He did not say whether he supported state bans that did not provide those exceptions, or whether he would vote for a measure enshrining abortion rights in his home state of Florida. And he did not address the experiences of women who have faced impossible choices and medical crises in states where the procedure is now banned.

“You must follow your heart, or in many cases, your religion or your faith,” he said. “Do what’s right for your family and do what’s right for yourself.”

Mr. Trump said later he believed his statement defanged what he saw as a toxic issue for his party by liberating Republicans to run on more politically favorable issues, including what he described on social media as “the Horrible Border, Inflation, Bad Economy, and the Death & Destruction of our Country!”

Some of the most stalwart anti-abortion champions said that as much as Mr. Trump wanted to neutralize the politics of the issue, he could not outrun what his presidency had unleashed. States across the country are enmeshed in battles over the details of their restrictions on the procedure, as Democrats push ballot measures across the country to enshrine abortion rights in state constitutions. Stories about women being denied the procedure continue to dominate the news. And the Supreme Court is expected to rule in June on curtailing access to a prominent medication used in abortion procedures.

Even as Mr. Trump’s views on whether he would sign a national abortion ban remain opaque, his allies and supporters are moving ahead with plans to restrict abortion rights with proposals and executive actions that could go beyond a national ban in a potential second Trump administration.

“Saying the abortion issue belongs in the states will not make it disappear from national elections,” Leonard A. Leo, a longtime leader of the Federalist Society who played an influential role in Mr. Trump’s selections for the Supreme Court, said in an interview.

Yet Mr. Trump’s comments underscored how the anti-abortion movement has struggled to find its footing in the post-Roe era. For decades, abortion opponents had one central goal of overturning Roe. Now, they face a political landscape radically reshaped by that decision, and a presumptive Republican presidential nominee who no longer sees them as an undeniable asset but as a potential political liability.

Over the weekend, leaders of anti-abortion groups started to get word that a statement from Mr. Trump was coming. They called around to try to learn what it would say.

Marjorie Dannenfelser, the president of Susan B. Anthony Pro-Life America, the leading anti-abortion group, said she spoke with Mr. Trump on Monday morning. Her group had extracted many promises from Mr. Trump in 2016 and frequently visited the White House. But it had failed in its push for Mr. Trump to endorse a federal 15-week ban.

“His concern is political only,” Ms. Dannenfelser said in an interview. “It is a huge disappointment. It is a total eclipse of reason, and that only happens in abortion politics for Republicans.”

Mr. Trump’s vice president, Mike Pence, called the announcement from his former boss a “slap in the face” to the anti-abortion voters who supported Mr. Trump in two previous elections. “Too many Republican politicians are all too ready to wash their hands of the battle for life,” he wrote on social media.

Mr. Trump reacted to the criticism with a series of scathing attacks on Ms. Dannenfelser and Senator Lindsey Graham of South Carolina, who also questioned the former president’s commitment to the anti-abortion movement on Monday. Mr. Trump took full credit for the decision to overturn Roe, disregarding the decades of work by activists and lawyers to build a conservative movement to undercut Roe.

“Lindsey, Marjorie, and others fought for years, unsuccessfully, until I came along and got the job done,” he posted on his social media site, Truth Social. “We cannot let our Country suffer any further damage by losing Elections on an issue that should always have been decided by the States, and now will be!”

Those who were less publicly critical did not face the same ire. Kristan Hawkins, the president of Students for Life, said Mr. Trump was “very clear affirming the family” in his statement. She was confident that if elected Mr. Trump would staff his administration with aides who would pursue efforts to further limit abortion rights and access across the country.

“I hope he sticks with this statement,” she said, “and then moves forward and starts naming pro-life appointments, naming his pro-life vice president pick, pledging that he is going to only appoint pro-life leaders to the Department of Justice, Health and Human Services, Department of Education, F.D.A., E.P.A., down the entire cabinet line.”

None of the critics said they planned on withholding their support for Mr. Trump in November, an indication that the former president may not pay a very high price for failing to adopt a more aggressive federal position.

The idea of a 15-week ban was always more about politics than policy. Such a proposal would not end many abortions. Nearly 94 percent of abortions happen before 13 weeks in pregnancy, according to data collected by the Centers for Disease Control and Prevention. Nor would such a ban be likely to capture enough support in the Senate for passage. And it would not affect the 18 states where abortion is currently banned before that point in pregnancy.

But it was unpopular among independent and moderate voters. Polling from KFF, a nonprofit organization focused on health policy, found that six in 10 voters opposed a federal ban after 16 weeks — a finding disputed by many anti-abortion advocates but not other Republican strategists.

“He hit all the right notes in this statement actually,” said Nicole McCleskey, a Republican pollster who has conducted focus groups about abortion. “He landed where the majority of most Americans are.”

Democrats disagree. They point to polling that shows most Americans support some form of abortion rights, and want to see those rights restored into federal law. From the White House to candidates in down-ballot races, Democrats were ready to pounce with a flurry of attacks that blamed the former president for what some called the “cruelty and the chaos” caused by abortion restrictions.

“Donald Trump made it clear once again today that he is — more than anyone in America — the person responsible for ending Roe v. Wade,” President Biden said in a statement. “Having created the chaos of overturning Roe, he’s trying to say, ‘Oh, never mind. Don’t punish me for that. I just want to win.’”

Democrats argued that Mr. Trump’s silence on the issue was effectively an endorsement of total bans in states such as Texas, where abortion is banned in nearly all circumstances. Their effort underscores the difficulty Mr. Trump may face as he tries to distance himself from an issue that will most likely remain in the headlines through Election Day and beyond.

“He understands acutely how unpopular his party’s position is on this and how unpopular his actions were,” said Mini Timmaraju, the president of Reproductive Freedom for All, an abortion rights group formerly known as NARAL Pro-Choice America. “He’s trying really hard to have it both ways, and we can’t let him get away with it.”

Within hours of Mr. Trump’s statement, Mr. Biden’s campaign released a digital ad spotlighting the story of a Texas woman who was denied an abortion, developed sepsis and may be unable to ever have another child.

In the ad, text flashes onto the screen. “Trump did this,” it reads, over the sounds of her sobs.