The Biden administration says nearly 24 million Americans selected a health plan for 2025 through Obamacare, marking another banner year for the program before President-elect Donald Trump and GOP majorities decide whether to weaken the Democrats’ prized law.

The administration said the plan selections through federal and state-run insurance portals exceeded the prior record of over 21 million in 2024.

Many customers renewed coverage for the 2025 plan year, though 3.2 million new customers joined them.

“Every year of the Biden-Harris administration we’ve set a new record,” said Neera Tanden, the domestic policy adviser to President Biden.

Open enrollment continues through Jan. 15 in many states, so the total number of 2025 signups should rise.

All told, 45 million Americans hold health coverage through Obamacare’s major expansion of Medicaid coverage for the poor or the insurance portals, which allow consumers to select private health plans and qualify for federal subsidies that defray premiums.

Mr. Biden supersized the subsidies through major legislation during his term, making the program more attractive and juicing enrollment.

His COVID-relief package in early 2021 boosted Obamacare assistance across the board and lifted the income cap for eligibility, delivering financial help to higher earners if benchmark premiums exceeded 8.5% of their income.

The enhanced subsidies were extended as part of Mr. Biden’s Inflation Reduction Act of 2022.

Whether the bigger subsidies stick around will be a key question as Mr. Trump and Republican majorities on Capitol Hill take control for at least the next two years.

The enhanced subsidies expire at the end of this year, and GOP lawmakers might want to trim them to save money and enact Mr. Trump’s ambitious tax-cut plans.

The Biden team is highlighting the stakes.

For instance, officials said some single Americans would see their premiums jump by $1,500 per year if the enhanced subsidies disappeared.

“I urge Congress to double down on the progress we have made and ensure Americans have access to quality, affordable health care by extending the ACA premium tax credit this year,” Mr. Biden said Tuesday, using an acronym for the Affordable Care Act, which is the formal name of the 2010 health law.

The Congressional Budget Office estimates that permanently extending the subsidies would add $335 billion to deficits over 10 years, though 3.4 million more people would gain insurance during that span.

Some Republicans are open to extending the subsidies given their constituents’ reliance on them.

“I think we’re going to have to,” Sen. Lisa Murkowski, Alaska Republican, told the Northern Journal in her home state.

“I don’t know what that may exactly look like — whether it’s just a straight extension, I don’t know. But I think we’re going to have to wrestle with this, and I think we’re going to be hearing a lot from our constituents on it,” she said.

Yet Mr. Trump is no fan of Obamacare.

He’s made it his white whale, pledging during the campaign to find ways to improve the law even as GOP lawmakers shied away from the program because of a disastrous repeal-and-replace effort in 2017.

Beyond the subsidy question, Mr. Trump hasn’t detailed what he would like to do with the program, famously stating at a September debate that he had “concepts of a plan.”

“If we come up with something I would only change it if we come up with something better and less expensive. And there are concepts and options we have to do that,” Mr. Trump said.

Republicans say Obamacare is a flawed model that throws taxpayer money at rising premiums instead of targeting the rising costs of health care.

Mr. Trump wants his pick to lead the Department of Health and Human Services, Robert F. Kennedy Jr. to “go wild on health” and prevent the root causes of disease and take a tough stance on drug companies that charge high prices.

In the meantime, the Biden team is touting Obamacare’s expansion as a major legacy item.

“The Affordable Care Act now stands along with Medicare, Medicaid and Social Security as one of the most consequential social programs in the history of our nation,” Health and Human Services Secretary Xavier Becerra said.

• Tom Howell Jr. can be reached at thowell@washingtontimes.com.