Almost 50 million Americans have had an Obamacare plan since 2014

WASHINGTON - Nearly 50 million Americans have been covered by health insurance plans through the Affordable Care Act's marketplaces since they opened a decade ago, according to tax data analyzed by the Treasury Department and published Tuesday.

Federal officials said that the findings represent roughly 1 in 7 U.S. residents, a broad swath of the population that underscores the vast, and seemingly irreversible, reach of the 2010 law.

The timing of the announcement was significant, coming just hours before the presidential debate in Philadelphia, where Vice President Kamala Harris will likely use the Affordable Care Act in her pitch to voters. The law has already featured heavily in her campaign stump speeches - a signal that Harris sees the issue as critical to swing state voters.

"More Americans now have health care than at any point in our nation's history," Harris said in a statement, adding, "President Biden and I will continue to use every tool at our disposal to strengthen the Affordable Care Act and reject efforts to repeal this landmark law."

Since President Joe Biden took office, more than 18 million Americans have enrolled in marketplace plans for the first time, federal officials said. In a record, roughly 21 million people signed up for one this year, a trend that health policy experts have largely attributed to major subsidies that have lowered premiums for many Americans purchasing plans.

Those subsidies, which cost the federal government tens of billions of dollars, are set to expire next year, likely setting off intense congressional negotiations over whether to extend them.

Biden repeatedly mentioned the Affordable Care Act in his June debate with former President Donald Trump, an early sign that Democrats were likely to make the issue central to their campaigns this summer.

Enrollment has been particularly high in states that have yet to expand their Medicaid programs to cover more adults, an option introduced by the Affordable Care Act that a vast majority of states have taken up.

Florida, Georgia and Texas - three large states that have yet to expand Medicaid - had significant numbers of residents flock to the marketplaces in the past decade. About 28% of people in Florida, 20% of people in Georgia and 19% of people in Texas have been enrolled at some point, the tax records show.

Harris and Gov. Tim Walz of Minnesota, her running mate, have repeatedly said that Trump, who tried unsuccessfully to repeal the law, would again seek to topple it if he wins the presidency. In 2020, the Justice Department under Trump asked the Supreme Court to overturn the law. After threatening a renewed repeal push late last year, Trump has recently kept his position vague, a signal of the Affordable Care Act's increasing popularity in recent years.

"We're going to keep the Affordable Care Act, unless we can do something much better," Trump said last month. "We'll keep it. It stinks. It's not good. If we can do something better, we're going to do something with it if we can do better, meaning less expensive and better health care for you."

Health policy experts have said that his administration could broadly undermine the Affordable Care Act in a kind of piecemeal fashion without seeking a repeal effort from congressional Republicans. And if the enhanced subsidies expire next year without being extended, many of those who have signed up for marketplace plans in recent years may forego one in 2026.

Some conservative experts have continued to argue that the law needs major reforms, criticizing the quality of plans and the cost of the subsidies that pay for them. Researchers at the Paragon Health Institute, a conservative policy research organization, said in a recent report that fewer Americans were enrolled in marketplace plans that had a broad range of providers in their network.

In previewing the data Monday, federal officials said that the numbers showed how versatile the marketplace offerings could be, covering some people continuously since 2014, others for just a few months at a time, and others in an on and off way when they have found other sources of coverage before coming back to a marketplace plan.

Filling in gaps in coverage is how the marketplaces are "contributing to a dynamic economy letting people change jobs or start a business without wondering how they'll ever replace their health insurance," said Aviva Aron-Dine, a health policy expert and the acting assistant secretary for tax policy at the Treasury Department.

More Americans have been eligible for subsidies in recent years, including families making more than 400% of the federal poverty level, or roughly $120,000 for a family of four. Researchers at the Urban Institute found in an analysis published Monday that older people in that income group particularly benefit from the enhanced subsidies.

This article originally appeared in The New York Times.