WASHINGTON — President Barack Obama has made suggestions for improving the Affordable Care Act (ACA), including bigger subsidies for private insurance and a Medicare-like public plan in some states.

Obama also said drug makers were putting their bottom lines ahead of the common good by opposing any constraints on medication prices.

“We worked successfully with some health care organizations and groups, such as major hospital associations, to redirect excessive Medicare payments to federal subsidies for the uninsured,” he noted. “Yet others, like the pharmaceutical industry, oppose any change to drug pricing, no matter how justifiable and modest, because they believe it threatens their profits.”

Obama’s views emerged in an online article in the Journal of the American Medical Association marking the sixth anniversary of the law’s enactment. “The ACA has succeeded in sharply increasing insurance coverage,” he wrote, saying that since it became law, the uninsured rate has declined by more than two-fifths, from 16% in 2010 to 9.1% in 2015, with most of the reduction occurring after the main coverage provisions took effect in 2014.

But the president conceded that health care and health insurance were still unaffordable for some people. Despite progress, “too many Americans still strain to pay for their physician visits and prescriptions, cover their deductibles, or pay their monthly insurance bills; struggle to navigate a complex, sometimes bewildering system; and remain uninsured,” he wrote. “More work to reform the health care system is ­necessary.”

The number of uninsured has decreased to 29 million, from 49 million six years ago, Obama said. To cut the number further, he called for more federal funding to help people get plans through online exchanges such as HealthCare.gov, which he said will be a viable source of coverage for decades. “However, both insurers and policy makers are still learning about the dynamics of an insurance market that includes all people regardless of any preexisting conditions, and further adjustments and recalibrations will likely be needed, as can be seen in some insurers’ proposed marketplace premiums for 2017,” he added.

Bringing up “a critical piece of unfinished business,” he noted that as of July 1, 19 states had yet to expand their Medicaid programs. “I hope that all 50 states take this option and expand coverage for their citizens in the coming years, as they did in the years following the creation of Medicaid and [the Children’s Health Insurance Program],” he said.

More than 9 million people with marketplace coverage receive tax credits that, on average, cover nearly 75% of their premium costs. Obama said the law was costing less than originally projected, so Congress could boost subsidies while still keeping costs below initial ­estimates.

Most of the country has benefited from the marketplaces, with 88% of enrollees living in counties with at least three insurers, which helps keep costs low, he said. However, the remaining 12% live in areas with only one or two insurers.

“Some parts of the country have struggled with limited insurance market competition for many years, which is one reason that, in the original debate over health reform, Congress considered and I supported including a Medicare-like public plan,” he wrote. “Public programs like Medicare often deliver care more cost-effectively by curtailing administrative overhead and securing better prices from providers. The public plan did not make it into the final legislation. Now, based on experience with the ACA, I think Congress should revisit a public plan to compete alongside private insurers in areas of the country where competition is limited.”

While the law included policies to help address prescription drug costs, such as bigger Medicaid rebates and a pathway for approval of biosimilars, “those costs remain a concern for Americans, employers and taxpayers alike — particularly in light of the 12% increase in prescription drug spending that occurred in 2014,” he added.

Congress should act on proposals like increasing transparency around manufacturers’ actual production and development costs, increasing the rebates drug markers are required to pay for drugs prescribed to certain Medicare and Medicaid beneficiaries, and giving the federal government authority to negotiate prices for certain high-price drugs, the president remarked.