WASHINGTON — President Obama announced Thursday that 8 million people have signed up for health insurance under the Affordable Care Act, including what White House officials said were a sufficient number of young, healthy adults, a critical milestone that might counter election-year attacks by Republicans on the law's success and viability.
The total number of enrollees exceeds by 1 million the target set by the administration for people to buy insurance through government-run health care exchanges. In particular, the number of young people signing up appears to have surged during the final weeks of enrollment.
"This thing is working," Obama said in the White House briefing room, in what amounted to a second victory lap after he announced two weeks ago that 7.1 million people had signed up for insurance during an initial enrollment period. "The Affordable Care Act is covering more people at less cost than most people would have predicted a few months ago."
Still, critics of the law cautioned that promising top-line numbers were not by themselves proof of success. Although more young people signed up for insurance, for example, the number remained below the level that some analysts believe is optimal for keeping premiums low in the insurance marketplaces.
The administration said 28 percent of those who bought policies were between the ages of 18 and 34, but some analysts said the optimum level would be 40 percent.
"In an ideal world, you'd want to get as close to that as possible," said Larry Levitt, a senior vice president at the Kaiser Family Foundation. "But what is important is what the insurance companies expected, and this is what they expected."
But the administration did not release two other crucial statistics that would help determine the success of the law: the number of people who bought insurance for the first time and the number who made their initial premium payments.
The number of those who were previously uninsured is important, since many people could simply have been moved from plans that were canceled under the law. Administration officials have promised to release that information when they have it, but they have said it is not data that is collected by the government.
Obama's remarks came a week after he announced the resignation of Kathleen Sebelius, his health and human services secretary. He spoke after meeting with state insurance commissioners, where he shared some of the new enrollment numbers.