It powered Democrats to recapture the House in the 2018 midterms: the fear that President Trump and Republicans would kill the Affordable Care Act and with it, protections for more than 50 million Americans with pre-existing medical conditions.
Yet even as Mr. Trump and other Republicans continue to try to overturn the law in court, Democratic presidential candidates have not made the issue central to their campaigns. Instead they have spent much of their time on the debate stage arguing among themselves over “Medicare for all” and other proposals to expand health coverage.
“I do think it’s a missed opportunity to educate voters about what’s really at stake in the fall,’’ said Leslie Dach, chairman of Protect Our Care, a group that ran a campaign-style war room in 2017 to defeat House Republicans seeking to repeal Obamacare, “and that’s having to stop Donald Trump’s relentless war on health care.”
Michael R. Bloomberg, the former New York City mayor who entered the Democratic presidential primary late and has not qualified to participate in the debates, has moved to exploit his rivals’ failure to mount a more frontal attack on Mr. Trump’s record on health care. Driven by extensive polling, Mr. Bloomberg’s campaign has released a torrent of television and digital ads accusing Mr. Trump of trying to “undermine coverage” for Americans with pre-existing conditions.
Since he announced his candidacy, Mr. Bloomberg has spent more than $88.2 million on television advertisements about health care in 27 states, according to Advertising Analytics, an ad tracking firm. About $66 million of those ads have attacked Mr. Trump on health care.
His campaign has spent $41.3 million airing one ad more than 46,000 times: It starts with a video clip of Mr. Trump saying “Let Obamacare implode.”
Another ad focusing on pre-existing conditions quickly got under Mr. Trump’s skin, prompting him to falsely claim in a post on Twitter that “I was the person who saved Pre-Existing Conditions in your health care.” Operatives for Mr. Trump’s campaign confirm that their own internal polling shows a strong Democratic advantage on health care.
“This is a really big negative for the president with swing voters,” said Howard Wolfson, a top adviser to Mr. Bloomberg. “Now having drawn blood, I think we’re going to continue in this vein.”
After a brief hiatus last week, the Bloomberg ad about pre-existing conditions was back on the air Friday through Monday. Mr. Bloomberg is now running another ad that notes that more people are uninsured under Mr. Trump than under President Obama.
A spokeswoman for Mr. Trump’s campaign defended the president’s record, claiming he “has protected Americans with pre-existing conditions by offering affordable health care with choice and patient-guided decision-making.” She also pointed to steps he’s taken to give people “access to short-term, limited duration plans and association health plans.”
But under the law, these cheaper plans are not required to cover pre-existing conditions. And Mr. Trump has for years sought the repeal of the Affordable Care Act, which includes a rule that people cannot be denied coverage or charged higher premiums because of their health status; both practices used to be widespread.
The second half of Mr. Bloomberg’s ad broadly touches on his own health care platform, announced in December. He proposes creating a so-called public option — an insurance plan that would be run by the government, and that people could buy with the health insurance subsidies that the Affordable Care Act currently provides.
The advertising blitz underscores the unorthodox nature of Mr. Bloomberg’s presidential campaign. He is not participating in the primary debates or regularly appearing on the stump, and is skipping the first four nominating states. He has shown no desire to spar with his Democratic rivals on health care, and is instead focusing his vast personal wealth on targeting the president. His strategy has helped him rise in some national polls, but has not translated into a move into the top tier.
Polling by his campaign found that health care costs are the top financial concern for families, and that a general sense of insecurity about health coverage is causing many voters to want to cling to the system they have.
With the Iowa caucuses less than two weeks away, some voters are voicing that anxiety.
Nathan Mundy, a lawyer from Des Moines, cited health care as a top concern as he waited for former Vice President Joseph R. Biden Jr. to speak at a campaign event in Indianola, Iowa, on Saturday.
“Elizabeth Warren backed off her Medicare for all stance,” he said approvingly. “I’m not a Medicare for all Democrat. I think Obamacare was the best solution possible. I really like Obamacare.”
Some analysts believe that Mr. Bloomberg’s strategy of attacking Mr. Trump now on political vulnerabilities could bring rewards in November.
“There’s this mistaken assumption in politics, like we’ve got this really good message, let’s save that till the end,” said Ken Goldstein, a professor of politics at the University of San Francisco. “I don’t think there’s much empirical evidence that there’s much value in saving something that’s good.”
“If the polling shows it is important, and then you manage to get a rise out of Donald Trump, stick your foot on the gas,” Mr. Goldstein said.
Support for maintaining Obamacare’s protections for people with pre-existing conditions has remained high over time. This past November, the Kaiser Family Foundation tracking poll found that 62 percent of the public — including 47 percent of Republicans — did not want the Supreme Court to overturn the protections.
And in September 2018, just before the midterm elections, the tracking poll found that 75 percent of the public overall and 58 percent of Republicans said it was “very important” that insurance companies could not deny coverage because of someone’s medical history.
The Trump administration has sided with Republican state officials in a lawsuit arguing that changes to the Affordable Care Act made by Congress in 2017 rendered its mandate requiring people to have health insurance unconstitutional, and that without the mandate, the law should fall. On that basis, a federal district judge declared the entire law unconstitutional in 2018, but an appeals court recently sent the case back to him for review.
The Supreme Court on Tuesday rejected a request from Democratic states to quickly consider the case; Mr. Trump and his Justice Department had made it clear to the court they were in no hurry to resolve it.
As Mr. Bloomberg’s ads blanket the airwaves, his Democratic rivals have spent most of their time going after one another, using health care as the vehicle to debate whether the party should nominate a moderate or a liberal seeking transformative change.
Lise Talbott, who works for a community health center in the Central Valley of California, in a congressional district that flipped to a Democrat in 2018 after a race dominated by health care, said she was surprised and disappointed that the Democrats running for president had not drawn more attention to Mr. Trump’s support of the lawsuit to overturn the law.
“The candidates seem to be in this battle over who’s going to get us closest to Medicare for all instead of talking about the care and coverage we have now and could lose,” Ms. Talbott said. “And because the candidates aren’t talking about it, I think a lot of people have sort of forgotten.”
Ms. Talbott, who supports Senator Elizabeth Warren of Massachusetts, was active in helping defeat Jeff Denham, her district’s former Republican congressman, after he voted with most other House Republicans in 2017 to repeal the Affordable Care Act. Mr. Denham’s successor, Josh Harder, talks frequently about protecting the law, she said.
Like Mr. Bloomberg, Mr. Trump seems to understand the power of warning people that they could lose something they like. At rallies and in speeches, he has repeatedly warned that the Democrats want to replace private insurance with a national single-payer health insurance program, or Medicare for all. (In truth, only Senator Bernie Sanders of Vermont and, to an extent, Ms. Warren, have embraced such a plan, with the other candidates calling for a “public option” that people could choose instead of private coverage.)
“The Democrats are pushing the socialist takeover of health care that would strip 180 million Americans of their private insurance plans and massively raise taxes on the middle class,” Mr. Trump said at a rally in Toledo, Ohio, this month. “A lot of you have private insurance plans that you love. They’re going to take them away from you.”
Whoever becomes the Democratic nominee will almost certainly make a huge issue of Mr. Trump’s attacks on the health law, as will Democrats running for the House and Senate.
“If you were to talk about the two things that mattered the most to people, it’s the pre-existing conditions and it’s the cost of health care,” said Mr. Dach, of Protect Our Care.
“Every candidate should be talking more about what’s wrong with Donald Trump as well as what they want to do” to improve health care, he added. “They should be able to walk and chew gum at the same time.’’
Maggie Haberman contributed reporting from New York and Katie Glueck from Indianola, Iowa.