Vice President Kamala Harris and her running mate Tim Walz, the Minnesota governor, have quickly made the Affordable Care Act central to their campaign, raising the specter of another Republican repeal effort next year if former President Donald J. Trump wins the White House.
“If Donald Trump gets the chance, he will end the Affordable Care Act and take us back to a time when insurance companies had the power to deny people with pre-existing conditions,” Ms. Harris said at a rally in Philadelphia last week as she introduced Mr. Walz as her running mate. “You remember what that was like?”
The next day, Mr. Walz said at a rally in Detroit that Mr. Trump would continue trying to undermine the 2010 health law because “he doesn’t care.”
But so far they are battling an opponent without a position.
Missing from the campaign this year is an organized effort against the Affordable Care Act by Republicans, who have tried and failed repeatedly to repeal the law. Mr. Trump threatened yet another repeal effort in November, but he walked his comments back in the spring, saying without specifics that he would make the health law “much better.”
“President Trump is not running to terminate the Affordable Care Act,” Karoline Leavitt, a Trump campaign spokeswoman, said in a statement. “He is running to make health care actually affordable.”
His running mate, JD Vance, echoed Mr. Trump’s in-between position when he told the news site NOTUS recently that past efforts to repeal the law were “fundamentally focused around the idea of fixing what was broken, not about stripping people’s health care away.”
“You’re certainly going to see efforts to reform the system,” Mr. Vance added.
The one-sidedness of the debate is a shift from the 2020 presidential campaign, when the Justice Department under Mr. Trump asked the Supreme Court to overturn the law. Although there were signs that year that Republican candidates were moving away from trying to repeal the act, Mr. Trump was still vowing to get rid of it, even as he failed to outline an alternative.
This year the Republican Party’s official platform, presented at the party’s convention last month in Milwaukee, included no mention of the Affordable Care Act, and few references to other health care reforms.
The absence of a Republican plan underscores how dramatically the politics of Obamacare have changed since the law was enacted, and since the Biden administration nearly doubled enrollment in its marketplaces through the use of subsidies that lowered the costs of plans.
About 21 million people signed up for plans in the most recent enrollment period, blowing by the previous record and elevating the health and political costs of a repeal.
Mr. Trump and Republican lawmakers have responded with what health policy experts call a strategy of ambiguity. After years of trying to get rid of the law, they have abandoned calls for a repeal but are broadly criticizing the costs and quality of plans on the Obamacare marketplaces. That approach amounts to a “shell game,” said Leslie Dach, a former adviser in the Obama and Biden health departments.
If Mr. Trump wins a second term, he may not need lawmakers to weaken the Affordable Care Act. Health policy experts say his administration could recycle its first-term agenda by reducing advertising and spending on workers who help people enroll in Obamacare plans, shortening enrollment periods and expanding the availability of cheap, short-term plans that shirk Affordable Care Act regulations. Those moves helped to cause enrollments to plateau when Mr. Trump was in office.
The most significant blow to the law could come from inaction. Mr. Trump and congressional Republicans are unlikely to support legislation that extends major subsidies that have lowered premiums for people with Obamacare plans and are set to expire next year. Experts have credited those subsidies for the boom in enrollment in recent years.
“Death by a thousand cuts,” said Sabrina Corlette, a research professor at Georgetown University’s Center on Health Insurance Reforms.
Democrats are operating in the friendliest environment they have had since Obamacare became law. Between 2010 and 2022, the uninsured rate among Black and Hispanic Americans was cut roughly in half, a trend that the Biden administration and outside experts attribute to the Affordable Care Act. More than 60 percent of Americans now have a favorable opinion of the law, according to a survey published in May by KFF, a nonprofit health policy research group.
As a presidential candidate in 2019, Ms. Harris pushed for a version of a Medicare for All plan. But her campaign told The New York Times in July that she no longer supported a single-payer health insurance system, a signal that she was likelier to focus on policies already advanced by Mr. Biden, such as the extension of the Affordable Care Act subsidies.
Kevin Munoz, a spokesman for the Harris campaign, pointed to comments Ms. Harris had made on the campaign trail. “When we win, Tim and I will continue to make the Affordable Care Act even stronger,” Ms. Harris said last week at the Philadelphia rally.
The Congressional Budget Office has estimated that extending the Obamacare subsidies would cost over $300 billion between 2025 to 2034, but lead to roughly 3.5 million more insured Americans each year.
Even if Mr. Trump were to win the White House with full Republican control of Congress, it is unclear how lawmakers would coalesce around a new repeal plan. After Mr. Trump threatened the law late last year, some Republican lawmakers suggested changing the marketplaces to improve the quality and affordability of plans. Others conceded there was little appetite for a repeal.
“We’re not in the same universe,” said Brian Blase, a former official in the Trump administration who now works at the conservative Paragon Health Institute. “There’s not going to be a replay of the large legislative package that happened in 2017.”
Mr. Blase said that anti-Obamacare Republicans have been mollified by reforms to the law like the halting of the individual mandate.
Alex M. Azar II, the former health and human services secretary under Mr. Trump, said that a future Republican administration would likely pursue more “technocratic” adjustments to the Affordable Care Act — a reflection of how difficult it would be to unwind the law. Some conservative think tanks, such as the Paragon Health Institute, have outlined an Obamacare agenda describing some of those likely changes.
Some policy recommendations are also incorporated in Project 2025, a Heritage Foundation-sponsored playbook for a possible second Trump administration developed in part by former Trump administration officials.
The project’s authors wrote that they were not calling for a repeal of the Affordable Care Act. The recommendations, they said, serve as “policy suggestions to curb the abuses” of the health law.
When Senator Jacky Rosen, a Nevada Democrat, won her seat six years ago, the Affordable Care Act was the dominant issue of her party’s midterm campaigns, helping reshape the power balance in Congress.
“In 2018, it’s all that we talked about,” said Ms. Rosen, who is now in another competitive Senate race.
Ms. Rosen’s opponent in 2018, Senator Dean Heller, voted for a version of a bill to repeal the Affordable Care Act in 2017 after being nudged by Mr. Trump. The move may have helped to cost him the race.
Nearly 100,000 people in Nevada signed up for Obamacare plans this year, the second-highest total in state history after 2022.
Ms. Rosen’s Republican opponent, Sam Brown, a Purple Heart recipient, represents the evolution of the Republican position on Obamacare.
“We need to resist it as much as we can,” he said in 2014 while running for a seat in the Texas Legislature. On his Senate campaign website this year, Mr. Brown says that “politicians have allowed bureaucrats to write health care laws, like Obamacare, that flood the marketplace with regulations — starving it of options — while driving up costs and lowering access to quality coverage.”
Ms. Rosen accused Mr. Brown of wanting to repeal the Affordable Care Act, something Mr. Brown denied. “It needs to be improved, and I will work on bipartisan solutions to bring down the cost of health care for every Nevadan,” he said in a statement. “The Affordable Care Act didn’t deliver on its promises of lowering costs and allowing people to keep their doctors. We need practical solutions that will actually deliver on these promises.”
Joe Grogan, the former director of the White House Domestic Policy Council under Mr. Trump, conceded that times had changed.
“I don’t see there being enough bandwidth to make a major charge at the A.C.A. even if there were people that wanted to do it,” he said. “You’d need far more consensus in the Republican Party to do that right now. And there are so many other things that are literally on fire.”
“You can’t fight on everything,” he said.