In addition to big decisions, like whether to expand Medicaid, some seemingly minor ones may have influenced the marketplaces’ health. Oklahoma has continued to allow about 45,000 people to keep old policies that do not meet Affordable Care Act standards. People with this type of “transitional” policy tend to be healthy, and may have helped the risk pool if they had been required to buy insurance through the exchange. Oklahoma is also one of three states that do not review insurers’ proposed rates from year to year, ceding the job to the federal government instead.

In New Mexico, on the other hand, insurance regulators did not allow people to keep their old plans and required any insurer that sold plans through the Affordable Care Act marketplace to offer them in every county. John G. Franchini, the state’s superintendent of insurance, has also negotiated rates with insurers, even denying a 52 percent increase requested by Blue Cross and Blue Shield of New Mexico for 2016.

Now, seven years after Mr. Obama signed the Affordable Care Act into law, Oklahoma is changing its stance and seeking a more active role. The state is preparing to ask the federal government’s permission to change how the law works here through waivers allowed under the law. One of its proposals is to help very poor people afford private plans by giving them subsidies.

The state may also ask for permission to “re-evaluate” and perhaps reduce the package of essential benefits that the Affordable Care Act requires every insurance plan to have. And it wants plans under the law to be sold not through the federal marketplace, but through a program called Insure Oklahoma, which has provided subsidized coverage to a subset of low-income residents here since before the health law took effect.