"We feel it's too soon to make a recommendation as to how the state should go forward," he said.

State officials can choose to adopt a state, regional or federal exchange, or a federal-state partnership under which the federal government runs certain aspects, such as electronic record-keeping, while the state handles customer service and other tasks.

State Sen. Jeremy Nordquist, who chairs of the National Conference of State Legislature's Health Committee and who has studied the insurance exchange program, said the Legislature should act before the court rules or it could be left scrambling to meet federal deadlines.

The court could decide the case as late as June 2012, but lawmakers are expected to adjourn in April. Nordquist said if the law is upheld then lawmakers would have to pass a bill in a special session before June 29 — the deadline to apply for a federal establishment grant worth tens of millions of dollars.

"We lose nothing by moving forward and enacting legislation," Nordquist said. "If we sit on our hands and the court upholds the law, we're going to be way behind the game, potentially to the point where the federal government says, 'Nebraska, you're not ready. We're going to run the exchange for you.'"

At least 16 states have enacted legislation to prepare for the exchanges, some of the new laws only establish advisory committees or take other early steps, said Kansas Insurance Commissioner Sandy Praeger, who chairs a health insurance panel for the National Association of Insurance Commissioners.

Praeger said state insurance officials may not know exact details of the minimum essential benefit plan until late winter or early spring in 2012. But she said states can still move forward to set up a basic exchange structure without knowing those details.

"You don't need that detail right away," she said. "But if you're not sure you want to do this at all, that would be a reason enough to delay."

She said states are struggling to set precise minimum coverage requirements because if they enact stricter requirements than the federal government's, they will have to pay the difference in costs for customers who qualify for a subsidy.

"Let's say a state has full mental health coverage, and the federal government only offers 30 days of inpatient hospital treatment," she said. "That's less expensive, because there's a cap. So whatever the difference is, the state would have to pay."

Federal officials will create an exchange for states that don't enact one of their own, Ramge said. Creating a state exchange would require legislation.

The state applied for a second federal grant of about $5.5 million in September to help study and design possible plans without committing to one, he said. The state received a $1 million grant last year to help plan for the change.

Nebraska is also waiting for a U.S. Supreme Court ruling to determine whether the federal health care law is constitutional. Heineman, a Republican, has said he would prefer to wait before the state commits to a plan.

The health care law, one of President Barack Obama's major domestic accomplishments, seeks to extend health insurance to more than 30 million Americans without coverage.

The state exchanges are meant to offer a one-stop-shop for Americans to buy health insurance. They must be federally certified by January 2013, operational by 2014 and self-sustaining by 2015.

The exchanges will include income-based tax credits to help pay for premiums.

State officials have said a regional exchange appears unlikely, because each state has different regulations and needs. A regional exchange also could lead to a concentration of jobs in one state at the expense of others.

A state-commissioned study released last August determined the new federal law will increase Nebraska's Medican costs by $526 million to $766 million over the next decade. In May, a state-by-state report commissioned by the Kaiser Commission on Medicaid and the Uninsured estimated a much lower cost of between $106 million and $155 million.