A handful of Arizona Republican legislators looking to overturn a 160-year-old state law that bans nearly all abortions have a new high-profile supporter: Kari Lake, a prominent Senate candidate and a close ally of Donald J. Trump.

The state Supreme Court’s ruling on Tuesday that upheld the 1864 law, from before Arizona was a state, set off a political firestorm, with Democrats predicting it would cause women to turn out in droves in a key swing state to protect access to abortion rights.

Now, some Republicans are looking for a way out of their political dilemma after their party blocked efforts to reverse the law. They see Ms. Lake, who is in a competitive race that could determine control of the Senate, as an important ally. Ms. Lake has called a handful of state legislators to offer her support in any effort to repeal the law and revert to the 15-week abortion ban that was in effect in Arizona, according to a person familiar with the outreach.

The new stance is an abrupt about-face for many Arizona Republicans, who cheered when the U.S. Supreme Court overturned Roe v. Wade in 2022 and then pushed quickly for reinstating the near-total ban from 1864. Ms. Lake herself had praised the 160-year-old ban during her 2022 run for governor, calling it a “great law,” but on Tuesday condemned the court decision, saying it was “out of step with Arizonans.”

Other Republicans followed suit.

“It is time for my legislative colleagues to find common ground of common sense: the first step is to repeal the territorial law,” State Senator Shawnna Bolick posted on X. It was a departure for Ms. Bolick, who once signed onto a law that would require prosecutors to charge women who have abortions with homicide and voted for the 15-week ban in 2022, legislation that included a provision allowing the 1864 law to go into effect.

The Republican backtracking reflects just how sharply public opinion has shifted on abortion since the Supreme Court’s consequential ruling, and how damaging the issue has been to their party. State laws on abortion enacted since Roe was overturned fueled strong showings by Democratic candidates in the 2022 midterms, and voters have turned out in force to protect abortion rights when they have been on the ballot, even in red states.

Still, the shift in tone went only so far. As Arizona Democrats clamored for votes and debate on proposals to repeal the 1864 ban on Wednesday, they were blocked by Republicans, who quickly shut down legislative proceedings and voted to adjourn until next week.

The 1864 law outlaws abortion from the moment of conception, with an exception only to save the life of a mother, and does not make allowances for rape or incest. The 15-week ban also lacks exceptions for rape or incest.

The State Senate president, Warren Petersen, and the State House speaker, Ben Toma, both Republicans, supported the abortion ban. Despite pressure from Democrats, women’s groups and even some Republicans, they have signaled they are in no hurry to repeal it.

“We as an elected body are going to take the time needed to listen to our constituents,” Mr. Toma said, adding that the Republican-controlled House would not “rush legislation on a topic of this magnitude.”

Democrats said it was urgent to pass a repeal before the court’s ruling upholding the 1864 law takes effect. “Today’s legislative action was unconscionable,” Gov. Katie Hobbs of Arizona, a Democrat, wrote on X. “The extremist Republican majority had the chance to do the right thing for their constituents, and they failed.”

Mr. Trump, after months of mixed signals — including privately telling allies he liked the idea of a 16-week federal ban — said this week that abortion restrictions should be left to the states, and then on Wednesday criticized the Arizona ruling and said he would not sign a federal ban.

Ms. Lake, who frequently stated her opposition to abortion on the campaign trail in 2022 and called it the “ultimate sin,” has been emblematic of a Republican shift on the issue. Last year, she said she opposed a federal ban on the procedure and would focus on passing policies giving financial benefits to women who chose to have children.

(On Tuesday, a Lake adviser claimed that the “great law” comment had been referring to the 15-week ban, signed by Gov. Doug Ducey in 2022. But Ms. Lake had referred to the near-total abortion ban by its number in Arizona’s state code, saying in a 2022 interview: “I’m incredibly thrilled that we are going to have a great law that’s already on the books. I believe it’s ARS 13-3603.”)

On Thursday, she posted a five-and-a-half-minute video on X, trying to carve out a middle ground on the issue by describing her own decision to have a baby.

“I agree with President Trump: We must have exceptions for rape, incest and the life of a mother,” Ms. Lake said in the video. “As your senator, I will oppose federal funding for abortion and federal banning of abortion.”

Other Arizona Republicans have come out against the near-total ban, including Representatives Juan Ciscomani and David Schweikert, both of whom are in competitive districts. Mr. Ciscomani said he still supported the 15-week ban, while Mr. Schweikert, who in the past cosponsored a bill that would have amounted to a federal abortion ban, called on the State Legislature “to address this issue immediately.”

Democrats highlighted the Republicans’ shift, saying they were hypocritical and papering over their anti-abortion histories.

“Arizona’s MAGA Republicans are lying about their long and detailed history of following Trump’s lead in taking away reproductive rights,” one email from the state Democratic Party read, echoing national Democrats’ messaging on abortion. Hannah Goss, a spokeswoman for Representative Ruben Gallego, the Democrat who is poised to face Ms. Lake, said her “longstanding record of wanting to ban abortion is clear.”

State Representative Stephanie Stahl Hamilton, a Democrat from southern Arizona, said that Democrats had introduced bills for six legislative sessions seeking to repeal the territorial-era ban, including a measure she introduced in January, but that Republican majorities had never allowed the measures to advance.

“I crafted a damn bill,” she said. “It just got ignored.”