The Affordable Care Act was conceived as a mix of publicly funded health care and privately purchased insurance, but Republican attacks, culminating this month in the death of a mandate that most Americans have insurance, are shifting the balance, giving the government a larger role than Democrats ever anticipated.


And while President Trump insisted again on Tuesday that the health law was “essentially” being repealed, what remains of it appears relatively stable and increasingly government-funded.

In short, President Barack Obama’s signature domestic achievement is becoming more like what conservatives despise — government-run health care — thanks in part to Republican efforts that are raising premiums for people without government assistance and allowing them to skirt coverage.

By ending the tax penalty for people who do not have coverage, beginning in 2019, Republicans may hasten the flight of customers who now pay the full cost of their insurance. Among those left behind under the umbrella of the Affordable Care Act would be people of modest means who qualify for Medicaid or receive sizable subsidies for private insurance.

“Republicans have inadvertently strengthened the hand of Democrats like me who prefer richer subsidies to a mandate and welcome the expanded federal role that will come with those subsidies,” said Joel S. Ario, a former insurance commissioner from Pennsylvania who worked in the Obama administration.

In days, the Trump administration is expected to carry out an executive order with proposed rules that would allow people to buy less expensive — and less comprehensive — coverage, through either business and professional associations or short-term private policies.

Mr. Trump and Republicans in Congress failed this year in their efforts to cut Medicaid and could try again in 2018. Speaker Paul D. Ryan said this month that Republicans would try next year to slow the growth of federal health spending because “it’s the health care entitlements that are the big drivers of our debt.”

But Senator Mitch McConnell, the majority leader, has been leery of another run at health care in an election year, and it is possible that Medicaid could, in the near future, actually grow further under the Affordable Care Act. Maine voters approved a referendum last month to expand Medicaid in that state, though Maine’s Republican governor, Paul R. LePage, is dragging his feet. Mr. LePage will not be on the ballot in November, when the state could elect a governor more willing to accept the referendum’s results.

Mr. Trump appeared to embrace some kind of bipartisan health care legislation on Tuesday with a Twitter post from his resort in Palm Beach, Fla.: “Based on the fact that the very unfair and unpopular Individual Mandate has been terminated as part of our Tax Cut Bill, which essentially Repeals (over time) ObamaCare, the Democrats & Republicans will eventually come together and develop a great new HealthCare plan!’’

Medicaid covers substantially more people than Medicare, the insurance program for older Americans. Even though only 31 states have expanded Medicaid, total enrollment is about the same as what the Congressional Budget Office was predicting in 2010, when it assumed that all states would expand eligibility under the Affordable Care Act. The Supreme Court ruled in 2012 that the expansion of Medicaid was an option for states, not a requirement.

Congress’s decision to eliminate the individual mandate means that healthier people with less need for insurance are less likely to buy it. The remaining pool of insurance buyers will have higher costs, on average, so insurers will increase premiums even more. And when premiums rise, consumers are entitled to larger subsidies from the federal government to help defray the higher costs.

In some ways, Medicaid is more generous than commercial insurers. The benefits are more comprehensive, and coverage is nearly free, with beneficiaries required to pay only nominal amounts. While Medicaid is a government program, most states contract with private insurers to deliver and manage care.

Among the few companies that have been successful on the Affordable Care Act exchanges are insurers like Centene that have experience in Medicaid.

“The reason so many people are on Medicaid,” said Sara Rosenbaum, a professor of health law and policy at George Washington University, “is that so many people have low incomes.”