Obama Says Young Adults Push Health Care Enrollment Above Targets

President Obama announced Thursday that eight million people had signed up for health insurance under the Affordable Care Act, and that 35 percent of them were under the age of 35, countering those who predicted it would attract mainly older and sicker people.

The final number exceeds by a million the target set by the administration for people to buy insurance through government-run health care exchanges. In addition, the number of young people signing up appears to have surged during the final weeks of enrollment.

“This thing is working,” Mr. Obama said. “The Affordable Care Act is covering more people at less cost than most people would have predicted a few months ago.”

The president’s remarks, delivered in the White House briefing room, amounted to a second victory lap after he announced two weeks ago that 7.1 million people had signed up for insurance during the initial enrollment period, which ended in March.

The administration extended the sign-up period by two weeks, until Tuesday, to accommodate late applicants, and the new numbers suggested that interest was running high.

While the number of younger applicants has risen, it remains below the level that some analysts believe is necessary for the long-term viability of the insurance marketplace. The administration said 28 percent of those who obtained policies were between the ages of 18 and 34; some analysts said the optimum level would be 40 percent.

Still, after a disastrous rollout because of a glitch-ridden government website, and the news last week that the secretary of health and human services, Kathleen Sebelius, would resign, the announcement on Thursday was further evidence that the president’s signature legislative initiative was enjoying a dramatic reversal of fortune.

Mr. Obama seized on the numbers to make his case that the law was a success, to challenge Republicans to drop their opposition to it, and to push states that have chosen not to carry out some of its provisions.

“I find it strange that the Republican position on this law is still stuck,” the president said. “They still can’t bring themselves to admit that the Affordable Care Act is working.”

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