Voters in Kansas and Missouri have long filled their legislatures with Republican lawmakers who oppose abortion. Those same Kansans and Missourians, when given the choice, have also voted in favor of abortion rights.

And though the word “abortion” did not appear on the ballot in either state on Tuesday, voters resoundingly shot down Republican-backed ballot measures that could have made it easier to ban the procedure in the future. In Kansas, voters rejected a proposal to start electing Supreme Court justices, and in Missouri, voters declined to make it harder for residents to amend the Constitution.

The results on Tuesday could buoy Democrats ahead of midterm elections as the party looks to gain power in Congress and hold several competitive governor’s seats, including in Kansas.

But voters in Republican-leaning states have a long history of siding with Democrats on ballot measures — on abortion, Medicaid expansion, minimum wage and more — while continuing to elect conservative politicians.

The Kansas connection to abortion was clearest: The state Supreme Court, made up overwhelmingly of justices appointed by Democratic governors, found in 2019 that the Kansas Constitution includes a right to abortion, frustrating Republican lawmakers who want to restrict or ban the procedure.

Then in 2022, Kansas voters rejected a Republican-backed ballot question that would have cleared the way for an abortion ban.

Lawmakers tried again this year by proposing a constitutional amendment that called for justices to be elected, rather than appointed by the governor and then put forward periodically for retention votes. Given the state’s rightward lean, the thinking went, an elected court would, over time, be filled with conservative jurists open to revisiting the abortion question.

But the amendment failed by a large margin on Tuesday, leaving in place a state Supreme Court with six Democratic appointees and one Republican appointee and likely securing abortion rights for the foreseeable future.

“Abortion rights are never entirely safe in Kansas,” said State Representative Stephanie Sawyer Clayton, a Democrat who opposed electing Supreme Court justices. “But does it keep us safe for the next couple of years? Yes, it does.”

Some supporters of electing the justices signaled that they would not drop the issue. State Representative Blake Carpenter, a Republican, wrote on social media that “I will continue fighting for a judiciary that is accountable to the people it serves.”

“I know there will be people who say this debate is over and that those of us who support reform should simply move on,” Mr. Carpenter wrote. “I disagree. If we believe the current system is unaccountable, then we have a responsibility to continue advocating for something better.”

One state to the east, Missouri Republicans have grown frustrated by a series of left-leaning policies that voters have enacted through ballot measures, particularly a constitutional amendment narrowly approved in 2024 that established a right to abortion.

On Tuesday, Missouri voters rejected an amendment proposed by lawmakers that would have required future citizen-sponsored constitutional amendments to be approved by a majority of voters in every congressional district, not the statewide majority that is currently required.

Given the ultraconservative makeup of some of those districts, passing a citizen-backed amendment to accomplish a policy goal of Democrats would have become exceedingly difficult.

Even after Tuesday, abortion will remain an unsettled question in Missouri. In November, voters will be asked to re-amend the state Constitution to remove abortion rights, which would effectively ban the procedure in the state.

The proposal raising the bar for constitutional amendments would not have changed the mechanics of that November vote. Lawmakers had carved out an exception for amendments proposed by the Legislature, like the upcoming one on abortion, which would have continued to need only a statewide majority to pass.

But if Missourians decide to remove abortion rights from the Constitution in November, abortion rights supporters would have had a much tougher time re-legalizing it had Tuesday’s measure passed. They could seek to place another referendum protecting abortion rights on a future ballot, but their odds of passing it would have been far slimmer.

At the polls in Kansas, many voters said their decision on whether to elect Supreme Court justices had nothing to do with abortion. Other Kansans on both sides of the abortion debate said they were aware of the stakes on that issue.

Standing outside her polling place in Leavenworth, Melany R. Blevins, 52, said she found the amendment issue confusing until she received a mailer from an anti-abortion group she trusted. She decided to support the amendment.

“They were definitely saying that yes was the way to go,” said Ms. Blevins, a Republican and a nurse’s aide.

In Lansing, Shawn O’Connor, 54, a government contractor and retired military officer, said he had opposed the amendment.

“To me, it’s just a ploy to get at the whole abortion tactics,” said Mr. O’Connor, who considers himself an independent but registered as a Democrat to vote in that party’s primary. “Kansas already voted on that, so let’s not try to make a ploy to change the court.”

Others said the integrity of the state court system, not abortion, drove their vote. Robert Ruckman, 72, a Democrat who said he was retired from the military, said he did “not want every year to have judges on TV declaring all their promises and all their things they’re going to do.”

“I don’t want them to get into the political system,” he said.