The clock is ticking on the exchange question in particular: states have until next Friday to decide whether they will build their own exchange or let the federal government run one for them. Some states have asked the administration for more time.

So far, only about 15 states and the District of Columbia have created the framework for exchanges through legislation or executive orders; three others have committed to running exchanges in partnership with the federal government. A number of Republican governors, including those in Arizona, Idaho, New Jersey, Virginia and Tennessee, had said they would decide after the election, giving themselves only a 10-day window before the deadline.

“I would expect that starting today there are a significant number of fascinating conversations going on behind closed doors in state capitols all over America,” said John McDonough, a professor of public health at Harvard who helped draft the law.

With deficit-reduction talks beginning in Washington next week, some observers believe that the law’s most expensive provisions — like federal subsidies to help families with incomes up to 400 percent of the poverty level pay their insurance premiums — could be scaled back in the name of deficit reduction.

“We know folks on the Hill are talking about this already,” said David Smith, an analyst at Leavitt Partners, a consulting firm that advises states on the law. “There are a lot of competing factors, but they have to find the savings and we believe health care will be one of the places where they will go.”

Another target for budget-cutters could be the planned expansion of Medicaid to people with incomes up to 133 percent of the poverty level — a crucial step toward the law’s goal of insuring about 30 million Americans.

When the Supreme Court upheld the health care law in June, it ruled that states do not have to participate in the expansion. For those that do, the federal government would pay the full cost for the first three years, starting in 2014, and gradually decrease its share to 90 percent in 2020 and beyond. As part of a deficit-reduction deal, Mr. Smith said, the Obama administration could agree to reduce the federal share.