In a House race in rural upstate New York, a congressional district containing some counties where Trump won by more than 22%, the Republican incumbent Elise Stefanik is campaigning on what would have been unthinkable five years ago: fixing Obamacare.

Stefanik is one of a wave of Republicans who, in the final weeks of the midterms election campaign, have advertised support for Obamacare’s most popular provisions. Republicans worked for the better part of a decade to repeal the law. Now, one Obamacare policy in particular has shockingly emerged as central to the right’s re-election push: protections for “pre-existing conditions”.

“I have family members with pre-existing conditions,” said Stefanik at a recent debate. “We have to protect people with pre-existing conditions,” she said, while attacking Democrats’ calls for universal healthcare.

“Pre-existing conditions” came into the lexicon after millions experienced a practice now banned by Obamacare, called “medical underwriting”. Medical underwriting allowed insurance companies to deny people coverage or charge more based on an individual’s health, if they did not receive health insurance through an employer.

Even people with minor conditions – depression, an abnormal pap smear, asthma – found themselves shut out of insurance through prohibitively expensive rates or outright coverage denial.

Now, after months of Republican silence on health insurance policy, GOP candidates have adopted an election strategy which denies how their own party would have undermined the protections they now claim support for, and even ignores their ongoing attempts to gut it.

For the Democrat challenging Stefanik, former St Lawrence county commissioner Tedra Cobb, Stefanik’s previous stance on healthcare pushed her into the race.

“For much of my career I have worked in healthcare,” said Cobb. The congressional district, New York’s 21st, stretches from the raceways of Saratoga Springs to the Canadian border. “But also, my daughter had a healthcare crisis, and when [Stefanik] voted to repeal the ACA, I was just so angry about pre-existing conditions.”

Observers suggest that Republicans are simply chasing something that is popular.

“The public opinion has shifted,” said Chris Sloan, a director at Avalere, a healthcare consulting company in Washington DC. While Republicans were not successful in repealing the law, there was “a lot of additional awareness made by both parties, talking about the provisions of the law, and some people realized the pre-existing conditions were a big part of it”.

“Many of the ACA repeal-and-replace bills last year had some language about pre-existing conditions protections,” said Sloan, “but it fell substantially short of the ACA.”

Americans know innately that life without health insurance can lead to financial ruin. One-in-four Americans younger than 65 have trouble paying medical bills, and medical debt contributes to hundreds of thousands of bankruptcies a year.

The US has the world’s most expensive health system. Each year, Americans spend more than $10,000 per person for healthcare. More than 17.9% of gross domestic product is spent on health, nearly double the 9.8% GDP Britain spends on health. Even routine procedures, such as giving birth, still cost thousands.

However, Republicans’ about-face has not gone unnoticed. In a locally televised debate, the moderator said the “majority” of questions, were about healthcare, including efforts to “repeal the Affordable Care Act”. Stefanik’s position has also come under scrutiny from a local newspaper, which called her statements on healthcare “misleading”.

Stefanik, “has a proven, bipartisan record of fighting to make healthcare and prescription drugs more affordable and more accessible,” her campaign told the Guardian. “The congresswoman has consistently fought to protect those with pre-existing conditions.” Stefanik’s campaign declined an interview request.

Stefanik does have a record of bipartisanship. But her strategy is not isolated in her party, including among its more extreme members.

President Trump has tweeted: “Republicans will totally protect people with Pre-Existing Conditions, Democrats will not!” He added: “Vote Republican.” Senior Republicans, such as Dana Rohrabacher of California, and those running for the Senate, like Missouri Republican challenger Josh Hawley, both pitched their support for protections already afforded by Obamacare.

“The public did not show major support for the ACA until the Republicans came up with a bill that was poorly crafted,” said Robert Moffitt, a health policy analyst at the conservative Heritage Foundation.

“If you think about it as a political matter – this is a political matter – it was a huge mistake,” said Moffit. “The whole thing was poorly handled.”

Poll after poll shows healthcare, and access to it, is a top priority for American voters. Problematically for Republicans, one of the most recent polls shows voters are more likely to trust Democrats to deal with health policy.

Now, Republicans’ high-profile attempt to undo Obamacare, which would have left 24 million people without insurance, looks increasingly like it weighs heavily on rank-and-file candidates. Even now, Republicans have no comprehensive plan to replace Obamacare, according to Moffit and others. Many in party leadership continue work to sabotage the law.

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Twenty Republican state attorneys are continuing a lawsuit to (again) try to overturn the law. And the Republican Senate majority leader, Mitch McConnell, said if Republicans win, he would (again) try to repeal Obamacare.

In four states changes to Medicaid, spearheaded by the Trump administration, added work requirements to the decades-old public health insurance program for the poor and disabled. In just one of those states, Arkansas, more than 4,300 people were booted from health plans because of the requirements. Seven more states have applications to add work requirements pending with the Trump administration.

Stefanik is likely to win her race for New York’s 21st district, but polls are narrowing. This midterm election is the first evidence of the ACA being “used successfully on offense”, in races like these, said Sloan.

For Cobb it’s very personal. Her daughter was just 17 when she was diagnosed with a degenerative disc in her back. She was beginning to lose function in her leg and bladder, when doctors quickly ordered her to get surgery for the condition. The family lost their employer-sponsored health insurance just one month later.

Today, they rely on the exchanges set up by Obamacare for health insurance, for which the family pays $16,000 per year. Should they need to use the insurance for a serious condition, it costs $10,000 more.

“Her surgery was in December, and I lost my insurance in January, and Elise [Stefanik] voted to repeal the ACA next summer,” said Cobb. “That’s when I said: ‘Im in.’”