Congressional Democrats have privately proposed a deal to Republicans that would extend expiring Affordable Care Act subsidies by one year, with lawmakers worried by new estimates that 2.2 million people will otherwise lose health coverage, according to five people who spoke on the condition of anonymity to discuss the proposal.

The move accompanied a broader package of health care proposals submitted to Republicans on Thursday night ahead of year-end spending negotiations.

Lawmakers are fiercely hammering out a bill to fund the government, and health care leaders are pushing to add priorities to one of the final pieces of legislation this Congress. Negotiations are also occurring on other measures, such as more funding for community health centers, proposals to address bipartisan frustrations about pharmacy benefit managers and other extensions of ongoing health care programs, four of the people said.

A one-year deal to extend the expiring ACA subsidies would avoid what was expected to be a bruising battle for both parties. Democrats, who crafted the subsidies and have fought to defend them, are set to lose control of the Senate and the White House next year, complicating their ability to make policy. Republicans, who are set to gain control of Washington, are wary of being punished by voters for any perception that they are rolling back health care coverage, with the backlash to their ACA repeal efforts still fresh in many lawmakers’ minds.

GOP leaders have repeatedly said they are skeptical of the subsidies, which expanded long-standing ACA tax credits to millions of Americans, and the influential House Republican Study Committee has called to end the nearly 4-year-old initiative.

It is not yet clear whether Republican leaders, who control the House, will agree to any of the proposals. Spokespeople for Republicans on the House Ways and Means and the Senate Finance committees declined to comment.

Democrats have prioritized the ACA subsidies given the number of people affected. Sen. Jeanne Shaheen (D-N.H.), Rep. Lauren Underwood (D-Ill.) and other Democrats have repeatedly pushed to extend the subsidies, which lower the cost of plans sold through the ACA’s insurance markets. The expansion of subsidies, which began as a pandemic-era effort to ensure that more Americans received health coverage, has been credited for helping increase ACA enrollment to a record 21 million people this year.

“Sen. Shaheen strongly supports extending these vital tax credits in the end of year package so millions of Americans can keep their insurance and taxes and costs don’t increase on working families,” Brendan Duff, a spokesman for the senator, said in a statement.

Republicans have decried the tax credits as an expensive federal giveaway, saying they distort the purpose of the ACA by subsidizing Americans who don’t need the assistance. Before the enhanced tax credits took effect, people with incomes above 400 percent of the federal poverty line — about $58,000 for an individual or $120,000 for a household of four people — were not eligible for assistance with ACA premiums.

Ahead of their proposal to Republicans, Democrats cited estimates released Thursday by the Congressional Budget Office, lawmakers’ nonpartisan bookkeeper, that projected a significant jump in the nation’s uninsured rate if the ACA credits are allowed to expire.

“Without a permanent extension, CBO estimates, the number of uninsured people will rise by 2.2 million in 2026, by 3.7 million in 2027, and by 3.8 million, on average, in each year over the 2026-2034 period,” Phillip L. Swagel, the CBO’s director, wrote to lawmakers.

“These savings are a lifeline, but if we don’t act now, Americans will see higher health care costs when these popular tax credits expire in 2025,” Underwood said in a statement Thursday.

Other estimates by outside groups have predicted even larger spikes in the uninsured rate.

The CBO earlier this year projected that permanently extending the tax credits would cost the federal government about $335 billion during the next 10 years. Democrats on Thursday night proposed paying for the one-year extension of the ACA subsidies by offsetting it with automatic spending cuts, invoking what is known as the budget sequester.

Advocacy groups have ramped up efforts to raise awareness of the subsidies and the risks of letting them expire.

“Democrats stand ready to extend the tax credits to ensure everyone has access to affordable health care,” Brad Woodhouse, executive director of Democrat-aligned advocacy group Protect Our Care, said in a statement Thursday. “It’s time for Republicans to get on board.”