WASHINGTON — The health care bill Republicans recently pushed through the House would leave 23 million Americans without insurance and confront others who have costly medical conditions with coverage that could prove unaffordable, Congress’ official budget analysts said Wednesday.

Premiums on average would fall compared with President Barack Obama’s health care overhaul — a chief goal of many Republicans — but that would be partly because policies would typically provide fewer benefits, said the report by the nonpartisan Congressional Budget Office.

In some regions, people with pre-existing medical conditions and others who were seriously ill “would ultimately be unable to purchase” robust coverage at premiums comparable to today’s prices, “if they could purchase at all,” the report said. That was a knock on 11th-hour changes Republicans made in the bill to gain conservatives’ votes by letting states get waivers to boost premiums on the ill and reduce coverage requirements.

The report said older people with lower income would disproportionately lose coverage. Over half of those becoming uninsured, 14 million people, would come from the bill’s $834 billion in cuts to Medicaid, which provides health coverage to poor and disabled people, over 10 years.

Democrats cited the analysis as further evidence that the GOP effort to repeal Obama’s 2010 law, a staple of Donald Trump’s presidential campaign and those of numerous Republican congressional candidates for years, would be destructive. It comes three weeks after the House narrowly passed the legislation with only Republican votes, and serves as a starting point for Senate Republicans trying to craft their own version, which they say will be different.

“The report makes clear that Trumpcare would be a cancer on the American health care system,” said Senate Minority Leader and New York Democrat Chuck Schumer, using the nickname Democrats have tried pinning on the bill. Schumer said the legislation would end up “causing costs to skyrocket, making coverage unaffordable for those with pre-existing conditions and many seniors, and kicking millions off of their health insurance.”

Trump’s Health and Human Services secretary, Tom Price, assailed the CBO for being inaccurate, with the White House issuing a similar critique.

“The CBO was wrong when they analyzed Obamacare’s effect on cost and coverage,” Price said of the agency’s report on Obama’s law, “and they are wrong again.”

Many congressional Republicans took a sharply different tack, emphasizing some of the report’s more positive findings.

“This CBO report again confirms that the American Health Care Act achieves our mission: lowering premiums and lowering the deficit. It is another positive step toward keeping our promise to repeal and replace Obamacare,” said House Speaker Paul Ryan, a Wisconsin Republican.

The analysis said the House bill, the American Health Care Act, would reduce federal deficits by $119 billion over the next decade. The previous version of the bill reduced shortfalls by $150 billion.

Trump and Republicans celebrated the House’s narrow May 4 passage of the bill in a Rose Garden ceremony after several embarrassing setbacks, even as GOP senators signaled it had little chance of becoming law without significant changes.

In a late compromise, House GOP conservatives and moderates struck a deal that would let states get federal waivers to permit insurers to charge higher premiums to some people in poor health, and to ignore the standard set of benefits required by Obama’s statute.

CBO said states adopting those waivers could destabilize coverage for people with medical problems. The agency estimated that about one-sixth of the population — more than 50 million people — live in states that would make substantial changes under the waivers.

The budget office projected that premiums in those states would be lower for healthy people than under current law because their coverage would be narrower, but did not estimate an amount.

For ill people in those states, “it would become more difficult” for seriously ill people to buy insurance “because their premiums would continue to increase rapidly,” the report said.

Benefits likely to be excluded from required coverage in some states would include maternity, mental health and substance abuse services, the report said. It said consumers’ out-of-pocket costs for those services “could increase by thousands of dollars in a given year for the (patients) who use those services.”

In states not getting waivers, where it estimated half the country lives, average premiums would be about 4 percent lower in 2026 than under Obama’s law, the report said. For the one-third of the nation where states would modestly reduce coverage requirements, average premiums would be about 20 percent lower, the analysts estimated.

The budget office said average premiums in those states would go down because younger and healthier people would buy coverage and the policies would cover less.

The report said that under Obama’s law, the nation’s health insurance market is expected to remain “stable in most areas” because federal subsidies to millions of consumers largely rise with premiums. Citing markets where insurers have left or sought huge premium increases, Republicans have repeatedly said the statute must be dismantled because it is in a death spiral.

Without naming the Trump administration, the report said factors encouraging insurers to flee some markets include lack of profits and “substantial uncertainty” about federal actions.