BOISE, Idaho — For years Democrats ran from the health care issue as though it were a heap of flaming rubble, which, politically speaking, it was.

Passage of the Affordable Care Act cost them control of Congress, gave rise to the upstart tea party movement and helped install Donald Trump in the White House.

But polls show support for the law increasing as it becomes more imperiled, and the result has been a political sea change.

A backlash to GOP repeal efforts has emboldened Democrats, who think they can seize back the House, dramatically expand coverage and turn health care from an albatross to an advantage even in red states such as Idaho, with the help of Republicans like Christy Perry.

The Idaho state representative is a down-the-line partisan who supports Trump, opposes abortion and boasts an A-plus rating from the National Rifle Association. But Perry breaks with many fellow conservatives when it comes to helping those who can’t afford insurance.

“People should be working and you should be carrying your own weight,” Perry said. “But we can’t just assume all people are created equal in this regard, because sometimes they’re not, and there are people who struggle with things through no fault of their own.”

Come November, voters in Idaho will likely weigh a ballot measure that would expand Medicaid to more than 60,000 hard-pressed residents, bypassing a conservative Legislature that has consistently blocked the move and thwarted advocates like Perry.

Similar end runs are being attempted in Nebraska and Utah, states Trump carried, where GOP lawmakers have also balked at extending coverage under the law.

In Montana, another Trump state, a petition drive is underway to continue Medicaid expansion beyond its scheduled June 2019 finish.

Democrats have gotten the message, campaigning on health care not just in blue states like California, or swing states like Nevada and Florida, but red states like Kentucky, home of Senate Majority Leader Mitch McConnell, who once vowed to eradicate the Affordable Care Act “root and branch.”

In Lexington, Ky., House hopeful Amy McGrath has attacked incumbent Republican Rep. Andy Barr for “enthusiastically” voting to strip health care coverage from more than a quarter-million Kentuckians — “many of the same kind of people,” she said in a campaign video, that her mother, a polio survivor, treated as a doctor.

The television spot, which helped catapult McGrath to an upset win in last month’s primary, is one of more than 26,000 health care-related ads broadcast by Democratic candidates across the country, according to Kantar Media’s Campaign Media Analysis Group.

“We haven’t seen anywhere we don’t think health care works as a political issue and also as a substantive issue,” said Brad Woodhouse, campaign director of Protect Our Care, an advocacy group fighting to buttress the Affordable Care Act.

The equation has clearly changed.

Democrats “don’t have to defend how the ACA works” as they did when President Barack Obama was in the White House, said Robert Blendon, a Harvard expert on health care politics.

“They just have to say, ‘The other party wants to take coverage away from millions of people,’?” he said.

Brad Woodhouse, a Democratic strategist, on the changed political dynamic surrounding the Affordable Care Act.

Last week, the Trump administration further roiled the debate by stating in court that it would not defend one of the law’s most popular provisions, which forbids insurance companies from denying coverage to customers with pre-existing conditions or charging them more.

Woodhouse can attest firsthand to the political shift. He was communications director at the Democratic National Committee in 2010, when Republicans campaigning against the ACA won 63 seats and took control of the House in a landslide.

Four years later, again promising repeal, the GOP claimed the Senate and won their biggest House majority since World War II.

In 2017, finally controlling both Congress and the White House, lawmakers set about to fulfill their pledge, failing by a single vote in the Senate when Arizona Republican John McCain delivered a dramatic thumbs-down.

By then, scores of GOP lawmakers were on the record supporting a rollback that would have resulted in 23 million fewer Americans having health insurance; like that, repeal was no longer a mere campaign slogan or partisan rallying point.

“Those threats were now very real,” said Jesse Ferguson, a campaign spokesman for congressional Democrats during several election cycles when they were clobbered by the health care issue.

Today, surveys suggest most Americans see the law in a generally positive light, a reversal from most of its eight-year history.

“Trump has polarized people around this issue and drawn the lines very clearly,” said Luke Mayville, who helped launch the Idaho drive by collecting signatures to put Medicaid expansion on the ballot.

Support is far from overwhelming, however, and Jesse Hunt, a spokesman for the GOP’s House campaign committee, said Republicans “were happy to litigate” the Affordable Care Act ahead of November.

Democrats “are responsible for the current problems that we have in our health care system as a result of Obamacare,” said Hunt, noting the law passed without a single Republican vote. “People still remember who started this mess.”

He suggested Democrats, if empowered, would make things worse through a government takeover of the health care system, a move backed by many on the left, including several 2020 presidential hopefuls.

Many running this year, however, aren’t pushing for a so-called single-payer system.

Rather, they promise to fight repeal of the Affordable Care Act — which the Trump administration continues to pursue — or call for expanding Medicaid, the federal program for the poor, disabled and nursing home residents that, polls show, enjoys strong support even among Republicans.

Here in Idaho, the focus is the estimated 62,000 residents who earn too much to qualify for Medicaid but not enough to pay for coverage through the state’s health care exchange. Legislators have fought over “the coverage gap” for years without resolving the issue.

Idaho’s secretary of state is expected to complete a review of signatures by mid-July, with preliminary tallies suggesting the initiative is all but certain to qualify for the November ballot.

The Idaho Freedom Foundation, a libertarian think tank that has been instrumental in blocking Medicaid expansion in the Legislature, is prepared to oppose the ballot measure.

mark.barabak@latimes.com