Continued from page 1

If states don’t expand their Medicaid programs, the government won’t be shelling out any help to Americans who don’t qualify for the current Medicaid program and earn below 100 percent of the poverty line, said Edwin Park, a health care specialist at the Center on Budget and Policy and Priorities.

“They have no Medicaid, they can’t get premium credits and unfortunately, they won’t get coverage,” Mr. Park said. “That’s clearly going to outweigh the increased cost for people between 100 and 133 percent of poverty.”

Still, that means they’ll be without insurance — eating into Mr. Obama’s goal of universal coverage.

Meanwhile, Republicans said that the court’s ruling stamping the mandate that all Americans obtain insurance a “tax” means Mr. Obama has violated his pledge not to raise taxes on the middle class.

Complicating matters is a provision in the law that bans the government from spending more than about half a percent of gross domestic product on insurance subsidies.

The government could hit that trigger if it has to pay out more insurance subsidies in the exchange, said Mr. Blahous, who has been a harsh critic of the way the CBO calculates the cost of the bill.