By Susan Kelly

(Reuters) - President Barack Obama on Monday urged Congress to reconsider offering a government-run health insurance option alongside private plans on the exchanges created as part of his national healthcare law.

In an article published in the online edition of the Journal of the American Medical Association, Obama said the Affordable Care Act had made much progress toward improving access to healthcare and the quality and affordability of care.

Many Republicans fiercely oppose the law saying it has raised health coverage costs for Americans and have tried repeatedly to repeal it in Congress

Obama said several challenges remain.

"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,” the president wrote.

Public programs like Medicare often deliver care more cost effectively by curtailing administrative overhead and securing better prices from providers, Obama said.

Republicans and some Democrats opposed the inclusion of a government-run plan similar to Medicare in the original Obamacare law, and the so-called "public option" did not make it into the final legislation.

Since the ACA became law, the uninsured rate has declined to 9.1 percent in 2015 from 16 percent in 2010. Most enrollees live in counties with at least three policy issuers, which helps keep down costs, Obama said.

However, 12 percent of those enrolled in plans through the exchanges live in areas with only one or two issuers. Adding a public plan in such areas would give consumers more affordable options, he said.

Obama also called on Congress to increase financial assistance to purchase coverage, which he said would help middle class families who are stilling struggling with premiums.

Obama said spending on prescription drugs, which rose 12 percent in 2014, remains a problem, and he urged Congress to act on his proposal to increase transparency around manufacturers' production and development costs. He said the federal government should be given the authority to negotiate prices for certain high-priced drugs.

Last month, Republicans in the U.S. House of Representatives unveiled a plan to overhaul the nation's healthcare system that would keep some of Obamacare's more popular provisions, including protections for people with pre-existing conditions and allowing young adults to stay on their parents' coverage until age 26.

The proposal, which is not formal legislation, is part of a broader effort by House Speaker Paul Ryan to offer a Republican agenda ahead of the Nov. 8 elections.

(Reporting by Susan Kelly in Chicago; Editing by Cynthia Osterman)