The Republican party’s "big, beautiful bill" would leave 10.9 million fewer people in the US with health coverage while cutting more than $1 trillion in spending from federal insurance programs over a decade, the nonpartisan Congressional Budget Office reported on Wednesday.

Most of the coverage losses would be due to changes in Medicaid, the health program for low-income, elderly, and disabled children and adults, including new work requirements that are expected to knock millions from its rolls. The rest would be due to reforms to the Affordable Care Act that could make buying insurance through its marketplaces more difficult while also limiting benefits for immigrants.

Healthcare experts have described the cuts as unlike any in history and warned that they would undo much of the progress the US has made in reducing the number of people without insurance since the Affordable Care Act passed in 2010.

“This would be the biggest rollback in federal support for healthcare ever,” Larry Levitt, executive vice president for health policy at the think tank KFF said on X.

The new numbers are similar to previous estimates from Capitol Hill, but they were updated to reflect the final version of the legislation passed by the House of Representatives last month and to show how different portions of the bill would interact with each other.

According to the CBO, the GOP’s legislation would reduce Medicaid enrollment by about 7.8 million. Much of the drop would be due to new rules requiring that able-bodied, childless adults spend at least 80 hours a month at work, in community service, or in an education program. The change is expected to shave $344 billion from the program, out of about $780 billion in total cuts.

The White House has tried to cast doubt on the CBO’s numbers, suggesting with little evidence that its staff may be politically biased. Other Republicans have argued that the office’s estimates are simply overblown and that the work rules are a “common sense” reform that won’t reduce coverage for individuals who truly need it.

“You’re telling me that you’re going to require the able-bodied, these young men, for example, to only work or volunteer in their community for 20 hours a week. And that’s too cumbersome for them?" House Speaker Mike Johnson said on this Sunday’s "Meet the Press." "I’m not buying it. The American people are not buying it."

But other healthcare experts have argued that work requirements are likely to block many Americans from coverage they are legally eligible for simply by piling on paperwork and red tape. They point to Arkansas’ brief attempt to impose work rules during the first Trump administration, which led to about 18,000 residents losing coverage even though “nearly everyone who was targeted by the policy already met the requirements,” as one study found.