Less than a month after a deadlocked Iowa Supreme Court left a six-week abortion ban unenforceable, lawmakers were set return to the State Capitol on Tuesday morning to consider a nearly identical set of restrictions on the procedure.

With large Republican majorities in both legislative chambers and a Republican governor who has decried “the inhumanity of abortion,” the new restrictions seemed very likely to pass.

“I believe the pro-life movement is the most important human rights cause of our time,” Gov. Kim Reynolds said last week when she called the special session on abortion. She also lamented the court’s deadlock, saying the “lack of action disregards the will of Iowa voters and lawmakers who will not rest until the unborn are protected by law.”

The session was expected to further cement Iowa’s sharp political shift to the right and end its increasingly rare status as a Republican-led state where abortions are allowed up to 20 weeks of pregnancy. The new limits would add Iowa to a list of conservative states, which includes Indiana, North Dakota and South Carolina, that have passed abortion restrictions since the U.S. Supreme Court ended the national right to abortion last year.

The call for a special session infuriated but did not surprise Iowa Democrats, who celebrated the court’s deadlock a few weeks ago but knew that Republicans were likely to try again. The Iowa Supreme Court’s deadlock left in place a lower court’s injunction that blocked enforcement of a six-week ban, but it also left unsettled the broader question of whether such restrictions are permissible under the state’s Constitution. Supporters of abortion rights said the new limits being considered by lawmakers endangered women’s health and ran counter to public opinion.

“We knew this would happen,” Senator Pam Jochum, the leader of the Democratic minority, said in a statement, adding that Republicans were “rushing to take away Iowans’ established rights and personal freedoms” and that they “hope they can do it fast enough that Iowans won’t even notice.”

The new bill introduced by Republicans allows for abortions up to about six weeks of pregnancy, before many women know they are pregnant. The bill includes exceptions after that point in situations involving rape or incest, in circumstances when the woman’s life is in serious danger or she faces a risk of certain permanent injuries or when fetal abnormalities “incompatible with life” are present.

Such restrictions on abortion in Iowa would further erode access to the procedure in the Midwest, where it is already limited. But a new law would almost certainly face a fresh legal challenge, and the outcome in the courts would again be uncertain.

Abortion is banned in almost all cases in the bordering states of Missouri, South Dakota and Wisconsin, and a new 12-week ban recently passed in Nebraska. Illinois and Minnesota, which are led by Democrats, have permissive abortion laws and could become destinations for Iowa women seeking abortions. More than 3,700 abortions were performed in Iowa in 2021, according to state data, most of them by medication.

A Des Moines Register/Mediacom Iowa poll from this year found that 61 percent of adults in the state believed abortion should be legal in most or all cases, while 35 percent believed it should be illegal in most or all cases.

But last year, when Democrats nationally ran on abortion rights, retaking state legislative chambers and holding governorships, the party floundered in Iowa, which not so long ago was viewed as a state where voters might swing to either party. Governor Reynolds won re-election in a landslide, Republicans swept the state’s congressional seats and voters unseated the attorney general and treasurer, both Democrats who had held office for decades.

Though Iowans voted twice for Barack Obama, and Democrats held a majority in the State Senate as recently as 2016, the state is now solidly Republican. Only one Democrat, Auditor Rob Sand, still holds statewide office, and the national Democratic Party has moved to push Iowa’s coveted first-in-the-nation caucuses later in the nominating calendar.

Republicans, for their part, have wasted no time remaking Iowa in a more conservative image. Ms. Reynolds signed laws this year that banned hormone therapy for transgender children, loosened child labor rules and limited the powers of Mr. Sand. And with Republicans keeping Iowa at the start of their nominating calendar, presidential hopefuls have been flooding the state.

State Representative Jennifer Konfrst, the leader of the Democratic minority in the Iowa House, said the state was not as conservative as recent election results suggested. Although Democrats are not likely to retake a legislative chamber next year, she said they saw an opportunity to expand their statehouse numbers in 2024 and regain a foothold in the congressional delegation. New abortion limits, she said, would have the potential to mobilize Democratic voters who sat out the last election.

“Our best case is going to be to hold Republicans accountable for going against what Iowans want,” said Ms. Konfrst, who represents parts of suburban Des Moines. “The fact that they’re hurrying it through in July, a year before an election, shows that politically they know this is unpopular.”

But Iowa Republicans have made no efforts to hide their support for abortion restrictions, and they have kept winning elections anyway. Matt Windschitl, the majority leader in the House, said, “Iowans have elected us on the promise to defend the unborn, and we will continue to follow through on that promise.”

The same poll that showed broad support for abortion rights this year also showed that more Iowans approved than disapproved of how the State Legislature was doing its job. And nearly two-thirds of those surveyed disapproved of President Biden’s job performance.