The Obama administration on Monday offered a surprisingly modest estimate of the number of people who would sign up for health insurance in the second round of open enrollment, which begins on Saturday.
Sylvia Mathews Burwell, the secretary of health and human services, said she was working on the assumption that a total of 9.1 million people would have such coverage at the end of next year.
By contrast, the Congressional Budget Office had estimated that 13 million people would be enrolled next year, with the total rising to 24 million in 2016. In the past, the White House has used the budget office numbers as a benchmark for success under the Affordable Care Act.
The new estimate appeared to be part of an effort by federal officials to lower public expectations, so the goal would be easier to meet and to surpass. In addition, the new number could indicate that administration officials believe it will be difficult to find and enroll many of the uninsured while retaining those who signed up in the last year.
“The number we are going to aim for this year is 9.1 million,” Ms. Burwell said on Monday during remarks at the Center for American Progress, a liberal research and advocacy group.
Ms. Burwell’s estimate was at the lower end of the range suggested by health policy experts in her department. In a report issued earlier Monday, the experts estimated that, at the end of next year, 9 million to 9.9 million people would have coverage purchased through insurance exchanges, or marketplaces.
Representative Marsha Blackburn, Republican of Tennessee, said the administration was “trying to manage expectations and rewrite its definition of success ahead of the second open-enrollment period.” Administration officials said they were just being realistic, in the light of experience with other health programs.
President Obama announced in April that eight million people had signed up for health insurance under the Affordable Care Act. Officials said Monday that enrollment had declined to 7.1 million after some people failed to pay their share of premiums and others were found to be ineligible because of unresolved questions about their citizenship or immigration status.
The Department of Health and Human Services estimated that enrollment, including renewals and new customers, would reach 10 million to 11 million by the end of the three-month sign-up period, which closes on Feb. 15.
However, if Ms. Burwell is right, the number would shrink to 9.1 million people at the end of next year. That would still be a 28 percent increase over the number believed to have marketplace coverage today.
Ms. Burwell’s estimate came as a surprise to insurance counselors, agents and brokers working with the Obama administration.
Anne Filipic, the president of Enroll America, a nonprofit group trying to expand coverage, said the goal of 9.1 million “seems reasonable.” She praised the administration for taking what she described as “a pragmatic, analytic approach” to setting a numeric goal.
Federal health officials said they had ended coverage for 112,000 people who could not demonstrate that they were United States citizens or legal immigrants entitled to insurance under the health care law.
In addition, they said, 120,000 households will lose some or all of the insurance subsidies they have been receiving because they could not adequately document their income. These households will face higher premiums.
In making their estimates, federal health officials said, they assumed that 83 percent of the people with marketplace coverage – 5.9 million of the 7.1 million people in “qualified health plans” – would renew their coverage.
The intense political debate swirling around the Affordable Care Act does not make the job of enrolling people any easier, officials said.
Republicans like Tom Cotton in Arkansas and Joni Ernst in Iowa won Senate races in which they emphasized opposition to the health care law, as did successful Republican House candidates like Mia Love in Utah and Ryan Zinke in Montana.
Senator John Barrasso of Wyoming, the chairman of the Senate Republican Policy Committee, said that people were skeptical of the law and “aren’t signing up because they realize it’s not a good deal for them.”
The Supreme Court said on Friday that it would consider a case challenging subsidies paid to more than four million people who obtained insurance through the federal marketplace.
Ms. Burwell said Monday that she did not see the legal challenge as a serious threat to the Affordable Care Act. “As we go into open enrollment,” she said, “nothing has changed.”
Federal health officials said they believed that marketplace enrollment would grow more slowly than projected by the Congressional Budget Office, which sees the total holding steady at 25 million from 2017 to 2024.
Administration officials noted that uninsured people could also get coverage by enrolling in Medicaid or by finding jobs with health benefits.
In a brief analysis of coverage trends, the Department of Health and Human Services said Monday that “most of the new marketplace enrollment for 2015 is likely to come from the ranks of the uninsured,” rather than from people who previously bought insurance on their own outside the exchanges.