In a campaign ad this month, Derek Tran, a Democrat from Orange County, California, blasted his opponent, Republican U.S. Rep. Michelle Steel, for supporting a national abortion ban and voting to limit access to birth control.

Democratic challenger Will Rollins also called out his rival, Rep. Ken Calvert, and “MAGA extremists” in an ad last week for their backing of a bill that could criminalize medical practitioners who provide abortions.

A few blocks from state Route 14 in Lancaster, about 70 miles north of downtown Los Angeles, Rep. Mike Garcia’s Democratic opponent, George Whitesides, planted two billboards promising to protect reproductive health care, a jab at the Republican congressman, who has voted to cut taxpayer funding of abortions for service members and other Americans.

As Election Day approaches, Democratic hopefuls are doing all they can to tie Republican opponents in contested congressional districts to their anti-abortion records. Aggressive ads are going up in California, Arizona, Nebraska, New Jersey, New York and Oregon, as Democrats see an opportunity to take control of the House by engaging voters who might not vote straight-ticket — or at all. Republicans currently control the House by a slim margin.

“What we all need to do is to make sure we look at her record, and that record is contrary to what she’s putting out there in her ads,” Tran said in an interview about Steel. “We’re making sure that we educate and remind the voters of who she really is.”

Democrats are also linking Republican incumbents to former President Donald Trump, who has taken credit for the 2022 Supreme Court decision overturning Roe v. Wade. Democrats are warning voters that more restrictions could come. During the Sept. 10 presidential debate, Trump dodged a question about whether he would veto a national abortion ban if elected.

A majority of voters support restoring a federal right to abortion, according to a recent KFF poll. And 1 in 14 voters say abortion is the most important issue in determining their choice. Those voters have the potential to make a difference in the close races, said David McCuan, a political science professor at Sonoma State University.

“The politics of abortion and reproductive health can get voters to participate at higher rates,” McCuan said. “It’s going to be a defining issue.”

Democrats are hoping the issue plays to their favor in California. Voters two years ago codified abortion rights into state law. In May, Planned Parenthood Affiliates of California launched a seven-figure campaign targeting seven Republican seats and Democrat Katie Porter’s open seat.

As a result, political analysts say, Republicans have shied away from their votes on abortion and some incumbents — such as Steel, Garcia and Central Valley U.S. Rep. David Valadao — have moderated their stances to appeal to voters.

Steel, like Garcia and Valadao, has said she supports exceptions to abortion bans in cases of rape, incest or threats to the life of the mother. All three co-sponsored a bill amounting to a blanket abortion ban in the previous Congress. Garcia and Valadao left their names off the bill last year, but Steel signed on again as a co-sponsor — briefly.

She withdrew her support after she won her March primary, explaining that it could create confusion because the three-page bill could threaten in vitro fertilization. In a September campaign ad, Steel shared that she had used IVF to have children and reiterated her support for the procedure. Steel spokesperson Lance Trover said she opposes a national abortion ban.

None of the Republican incumbents who represent a California “toss-up” district, as determined by the nonpartisan Cook Political Report, granted KFF Health News an interview. Those who did respond said they do not support a national abortion ban.

Rep. John Duarte added that he opposes a ban because he’s “pro-choice,” and Calvert said “the issue is best decided with the states and their voters directly.” Both voted for a bill to limit medication abortion and supported a measure that would have authorized prison time for medical providers who don’t resuscitate babies born after an attempted abortion.

Tim Rosales, a political strategist who has represented Republican candidates, said these incumbents shouldn’t get heat for changing their minds over time, noting that Democratic former Presidents Bill Clinton and Barack Obama reversed their positions on same-sex marriage.

“There has to be some allowance for evolution on a variety of issues,” Rosales said.

Ben Petersen, a spokesperson for the National Republican Congressional Committee, said Democrats who have called out Republicans for inconsistencies want to move the conversation away from other topics, such as the “disastrous cost of living crisis hurting women and families caused by their one-party control of Sacramento.”

This political dance is playing out on the national stage, especially in battleground races where Republicans find themselves on defense in states where abortion is on the ballot. Roughly two dozen races are considered toss-ups.

In a March post on the social platform X, Republican Nebraska Rep. Don Bacon wrote, “I’ve always defended the life of the mother,” after his Democratic rival, Tony Vargas, called him out for supporting a national abortion ban, which makes no exceptions for cases in which the mother’s life is at risk. That same month, Rolling Stone reported that the Omaha-area congressman had deleted some anti-abortion endorsements from his website. Nebraskans will vote this November on competing abortion ballot measures.

In Arizona, where voters will also be asked whether to enshrine abortion rights into the state constitution, Republican incumbent David Schweikert this year did not support a national abortion ban, which he had co-sponsored at least six times from 2012 to 2021. In April, he wrote on X that he opposed an abortion ban in Arizona, calling on the state legislature to “address this issue immediately.”

On the airwaves, on their websites, and on the campaign trail, Republican candidates are pivoting to convince voters that they have voted to protect women. For example, Steel this month released an ad titled “Champion,” in which the Orange County sheriff says Steel has “worked tirelessly to protect victims of domestic violence and sexual abuse.”

Trover, the Steel spokesperson, said she voted two years ago to reauthorize the Violence Against Women Act. That vote was on a larger $1.5 trillion government spending bill, which included the measure.

The year before, Steel voted against reauthorizing the act.

This article was produced by KFF Health News, a national newsroom that produces in-depth journalism about health issues and is one of the core operating programs at KFF — the independent source for health policy research, polling and journalism. KFF Health News is the publisher of California Healthline, an editorially independent service of the California Health Care Foundation.