Insurers are worried about measures that might create “an unlevel playing field,” according to Holland, a former Oklahoma insurance commissioner, speaking in a telephone interview. “Anything that would create market variation or lack of consistency would be problematic.”

Daryl Richard, a UnitedHealth spokesman, said the Minnetonka, Minnesota-based company is in the process of researching how each of the state’s exchanges may be structured.

“Given the regulatory variation from state to state -- and many states have not yet formalized their exchange models -- we have not yet made any decisions about where we will be offering our health plans through the exchanges,” Richard said.

UnitedHealth is not the only for-profit insurer looking at the exchanges warily, said Robert Zirkelbach, a spokesman for America’s Health Insurance Plans, the industry’s lobbying group in Washington.

The group has generally opposed practices like those of Connecticut, a model called “active purchasing” through which some insurers may be excluded from selling their plans, he said.

Maximizing Choice

“There’s already variation in how health insurance is regulated state by state,” Zirkelbach said in a telephone interview. “The important thing is how the exchanges are structured, ensuring they’re done in a way that will maximize choice and competition for consumers and employers.”

States with extra rules run the risk that insurers won’t participate in their exchanges, said Ana Gupte, an analyst with Sanford C. Bernstein & Co. in New York.

“I’m sure the insurance industry will go in with good faith of wanting to play everywhere they possibly can, but they can always reduce their effort and involvement over time,” she said in a phone interview. “It’s a balance, because you do want the large publicly traded players and the big Blue Cross Blue Shield to of course all be there, in addition to the smaller not-for-profits.”

A majority of the remaining 50 U.S. states may let the U.S. run the markets or choose to provide services such as consumer assistance in a partnership with the federal government.