The One Big Beautiful Bill Act, which was passed by the House last month, would advance one of the long-term goals of the Republican Party: to diminish the number of enrollments in Obamacare.

The numbers are not finalized, but experts estimate that between 8 million and 15 million people may lose health insurance coverage through significant alterations the legislation makes to marketplace exchange plans and the Medicaid expansion included in Obamacare.

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President Donald Trump pledged to repeal and replace Obamacare in his 2016 presidential campaign and attempted to follow through on that promise early in his tenure. The repeal effort failed, but now, his “big, beautiful bill” would make changes to Obamacare that would have far-reaching effects for the program.

Although Trump and House Speaker Mike Johnson (R-LA) maintain that the legislation is not a healthcare bill, the version of the reconciliation bill passed by the House in May makes a number of substantive changes to Obamacare, including shortening the open enrollment period, barring beneficiaries from self-attesting changes in income, and eliminating automatic enrollments into marketplace plans. 

The bill also makes Deferred Action for Childhood Arrivals, or DACA, recipients ineligible to purchase exchange plans, reversing a policy implemented by former President Joe Biden. It also limits subsidized marketplace coverage to lawful permanent residents, or green-card holders, and a small subset of other immigrants.

The “big, beautiful bill” also would change Medicaid expansion under the Obamacare framework in several ways, affecting low-income, able-bodied adults without dependent children. 

Although the bill does not rein in Medicaid expansion spending as much as fiscal hawks in the House hoped, it eliminates the temporary financial incentive for states that newly adopt the expansion instituted under the Biden-era American Rescue Plan Act, according to an analysis from the health policy think tank KFF.

The bill also institutes work requirements for adults covered by the Medicaid expansion, which policy experts say will result in a loss of coverage due to administrative difficulties for beneficiaries reporting their work hours, in addition to coverage losses from Marketplace exchange programs.

The work requirements specifically apply to able-bodied adults, ages 19 to 64, with no dependent children, who must show they worked, volunteered, or attended school for 80 hours per month. The bill includes some exemptions for pregnant women and newly released incarcerated people.  

A spokesperson for the Energy and Commerce Committee, in which many of the program changes originated, told the Washington Examiner that “repealing and replacing Obamacare was never part of the conversation.”

“This reconciliation funding exercise was to root [out] waste, fraud, and abuse across the entire federal government. Congressional Republicans achieved this by ensuring program integrity of programs like Medicaid,” the spokesperson said.

Reducing program bloat

White House spokesman Kush Desai told the Washington Examiner that the legislation “offers Americans better options and implements commonsense changes” that address waste, fraud, and abuse in Obamacare. 

“President Trump will continue to deliver on his promises to reduce health insurance costs and empower consumer choice,” Desai said.

Aaron Evans, president of Winning Republican Strategies, told the Washington Examiner that “the ACA is bloated.”

“The bloated subsidies of the ACA have driven up premiums 30% since 2017, and I think that we’re seeing Republicans push real reforms to make healthcare more affordable, not just throwing more money at a broken system,” Evans said. 

Enrollment in Obamacare exchange plans reached nearly 24 million during the 2025 open enrollment period, double the level of the 2021 enrollment period, during the last full year of the first Trump administration.

That increase in enrollment is largely due to expanded premium tax credits for people already eligible for assistance, which Democrats implemented in 2021 as part of Biden’s American Rescue Plan. Those tax credits were extended in 2022 by the Inflation Reduction Act but are set to expire by the end of the year. 

While extending premium tax credits could be taken up by the legislature later this year, they are not included in the reconciliation bill. 

Medicaid enrollment also grew substantially over the past few years, largely due to temporary coverage expansions made during the COVID-19 pandemic, peaking at 87.3 million enrollees in April 2023. 

That’s fallen to 71.3 million as of December 2024, still significantly higher than the 64.5 million in February 2020.

Trump’s history with Obamacare

Cynthia Cox, an expert for the healthcare think tank KFF, said the provisions of the GOP megabill “look pretty similar to a lot of the things that the Trump administration had done before or would have liked to do.”

On his first day as president in 2017, Trump signed an executive order minimizing the economic burden of Obamacare pending repeal, a first step toward repealing the law.

Those efforts failed in 2017, when the late GOP Sen. John McCain famously gave a thumbs-down, signaling a “no” vote on the Health Care Freedom Act. His actions earned him a phone call from former President Barack Obama, to whom he lost the 2008 presidential election, and scorn from Trump. 

Trump scored some success when his signature 2017 tax cut legislation eliminated the Obamacare individual mandate for coverage. Soon after, Congress repealed the Obamacare provision authorizing the Independent Payment Advisory Board, decried by conservatives as “death panels,” which were meant to slow growth in Medicare federal spending. 

In November 2020, Trump’s administration, backed by Republican officials in nearly 20 states, asked the Supreme Court to overturn Obamacare. The bid was unsuccessful. In June 2021, the high court ruled 7-2 that the lawsuit had no legal standing. 

On the 2024 campaign trail, Trump said during a debate that he had “concepts of a plan” to replace Obamacare.

Several weeks later, now-Vice President JD Vance defended his running mate’s plans, claiming that Trump saved Obamacare from collapsing under its own administrative weight during his first term.

In the first five months of his second term, Trump has largely focused on issuing executive orders aimed at lowering healthcare prices for the public.

“We’re probably looking at millions more uninsured, but the Obamacare markets will continue to function,” Cox said. “Whereas, with some of the versions of the repeal and replace proposals that had been floated around in 2017, some of those would have left the markets very unstable, to the point that some markets might not have even worked at all.”

Technical policies and the uninsured rate

Drew Altman, CEO of the healthcare policy think tank KFF,  said in an essay on the bill earlier in May that the policy changes included in the Republican reconciliation bill “are obscure and in the weeds, but enormously important for people and the Marketplaces in every state.” 

Because of the policy nuances, it’s difficult to determine the number of people who will become uninsured if the policies take effect as written in the House version of the bill. 

Higher estimates for the number of disenrollees, upward of 15 million, come from including the effects of the expiring premium tax cuts in calculations. 

If Republicans and Democrats come together to renew premium subsidies before the end of the year, apart from the reconciliation bill, then the number of disenrollees could be under 8 million.

Any figures, however, are murky at best. The Congressional Budget Office has not issued its estimates of the House version of the bill, in part because it’s tricky to discern how the nuances of the policy provisions will interact with each other in the real world.

“It’s hard to say what’s going to happen there, because some of those provisions overlap with each other or conflict with each other in different ways,” Cox said. 

Republicans have pushed back against the CBO’s estimates that “the expiration of the expanded premium tax credits will increase the number of people without health insurance by 4.2 million in 2034.” In total, the report also estimates that at least 8.6 million people will be without insurance in 2034.

The estimates were released at the behest of the Democrats on the Energy and Commerce Committee. 

Republicans cited the CBO’s past overestimates of Obamacare exchange enrollment as a reason not to trust its current projections. An analysis from the Commonwealth Fund showed that the CBO overestimated marketplace enrollment by 30% and marketplace costs by 28%. In contrast, the CBO underestimated Medicaid enrollment by roughly 14%.

“Under this bill, the integrity of the Medicaid program will be restored as we allow Medicaid to [serve] and assist the Americans it was intended to support: Expectant mothers, children, low-income seniors, and people with disabilities,” the Energy and Commerce Committee spokesperson said.

Evans, the GOP strategist, added that concerns from Democrats, especially about premium prices and uninsured numbers, obfuscate the benefits the bill would confer in terms of rectifying the program’s administrative problems. 

“One of the things we’re going to hear from the Democrats is they’re going to talk about 75% premium hikes and all the other things,” Evans said. “But ultimately, what we’re really seeing happen here is trying to address some problems that have existed from the very beginning with ACA, most Americans will still get their subsidies. And then, you know, future plans will tackle costs for good, but it has to start somewhere.”

Senate Republicans as a moderating voice

The Republican legislative bill could face sweeping changes during the Senate’s half of the legislative process, as a handful of centrist Republicans have expressed disapproval of how the bill will impact Medicaid benefits, along with the healthcare impact on rural hospitals and tribal nations.

Sen. Susan Collins (R-ME) said while visiting Maine last Tuesday that she believes the Senate can “make the bill much better.” 

“I’ve said that if there are deep cuts in Medicaid that would endanger healthcare for low-income families, for disabled children, for other vulnerable populations, and for our rural hospitals, I’m simply not going to support that,” Collins told constituents. 

A spokesperson for Collins told the Washington Examiner that the healthcare provisions of the bill are unlikely to pass the Senate in their current form but did not elaborate on the negotiation process.

Other centrist senators remained mum when the Washington Examiner reached out for comment on their support of the provision rollbacks.