But the administration's final numbers, released Thursday, also expose shortcomings, including subpar enrollment among Hispanics, the nation's largest minority group and also its least insured.
Still, strong state-by-state performance indicates that the health care law is making inroads around the country, even as Republicans insist repealing "Obamacare" will be a winning issue in the fall congressional elections. An Associated Press analysis of the government numbers found that 31 states met or exceeded enrollment targets set by the administration before the insurance exchanges opened. Twenty of those are led by Republican governors, many of whom were hostile to the program.
The Health and Human Services Department said 8 million Americans chose a health plan through the new insurance markets in the first year of the historic health care overhaul. Some 4.8 million more gained coverage through Medicaid and children's insurance programs. A surge in enrollments since March 1 doubled sign-ups in some states, including Texas, Georgia and Florida.
"There is reason to be optimistic about what the law can deliver, both in terms of coverage and affordable insurance options" said Andy Hyman of the nonpartisan Robert Wood Johnson Foundation. "In time, it will become part of the bloodstream of our health care system." Hyman is a senior program officer working to expand coverage.
With Republicans vowing to make the failures of the law a main theme of their midterm election push, the Obama administration will need to convince the public that it has been a success. A recent administration announcement of the 8 million sign-ups failed to move public opinion much, with negative views of the law more common than positive ones. But polls also have found that Americans don't want the law repealed, preferring that Congress work to improve it instead.
Younger and healthier than the U.S. population as a whole, Hispanics had been viewed as crucial to the success of Obama's coverage expansion. But the final count was disappointing. Hispanics account for 14.5 percent of those eligible for coverage on the new health insurance markets, but they represented 10.7 percent of the actual enrollees who also volunteered their race or ethnicity, the government reported.
Many Hispanics tried to get coverage but hit roadblocks, said Jane Delgado, president of the National Alliance for Hispanic Health, a nonpartisan advocacy network. The reasons are numerous: A Spanish version of the federal health care website was delayed and there was a shortage of in-person guides reaching out to Latinos.
For some mixed-status families, a fear of immigration authorities may have discouraged enrollment. Immigrants who are in the United States illegally cannot participate in the new health insurance system, but many have eligible relatives who are citizens or legal residents.
"This is only the first step in a long race," Delgado said. "Many people who are uninsured don't understand the language of insurance. Big media campaigns aren't as effective for actual enrollment as the one-on-one approach."
The new report didn't include information on how many of the newly enrolled have actually paid their insurance premiums. With grace periods for enrolling extending into mid-April, many who have signed up weren't obligated to pay until this week. A report released Wednesday by House Republicans said 67 percent of people who had signed up through federal marketplaces had paid their first month's premiums as of April 15, far lower than payment rates reported by some individual insurers, which were more in the range of 85 percent or above.
White House press secretary Jay Carney said Thursday it was no surprise that GOP lawmakers who have voted to repeal the law would put out a downbeat report about the law's progress. He said official figures on paid premiums would come out when the complete data that is currently being compiled is ready. "I'm confident it's not going to be 67 percent. I don't know what it's going to be," Carney said.
Even though the administration is claiming huge successes, the Congressional Budget Office projects more than 40 million people will still be uninsured this year, and a more complete picture of who's still uninsured won't emerge until next year with the first results from large national surveys.
"Beyond a doubt, the number of uninsured Americans has fallen by millions. Whether it's 5 million or 15 million still isn't clear," said Larry Levitt, an expert on health insurance markets at the nonpartisan Kaiser Family Foundation. "The low enrollment among Latinos is an indication of where challenges still lie: the hard-to-reach groups where more outreach is probably needed."
Many of the underperforming states were those that had built their own online marketplaces. Massachusetts, which had served as a model for the Obama program, only signed up 31,695 people, far short of the goal of 250,000. Oregon, which met only 29 percent of its goal, recently decided to scrap its online marketplace and go with the federal portal.
Other highlights of the report:
—Young adults aged 18 to 34, whose premiums are needed to balance the cost of older, sicker enrollees, made up about 28 percent of the total 8 million. Independent analysts have said the mix should be 40 percent young adults. But the administration called the mix sufficient to keep premiums stable.
—More women than men signed up through the exchanges: 54 percent vs. 46 percent.
—It's still not clear how many people who purchased coverage on the new markets already had insurance. The report said of the 5.18 million who applied for financial assistance and selected a plan on the exchanges run by the federal government, 13 percent said they already had coverage.
—Blacks and Asians signed up at higher-than-expected rates. Blacks make up 13.3 percent of those eligible for marketplace coverage, but represented 16.7 percent of those who chose a health plan and disclosed their race. Asians make up 3.3 percent of the eligible pool, but were 7.9 percent of enrollees who volunteered racial information.
—Nearly a third of people who chose a health plan on the federal exchanges didn't report their race or ethnicity, or chose "Other."
The next enrollment period for private health insurance coverage for 2015 under the health law is scheduled to run Nov. 15 through Feb. 15.
"They've had some success," Levitt said, "but they're going to have to do it all over again next year and get more people signed up to succeed."
Associated Press writers Ricardo Alonso-Zaldivar, Kevin Vineys and Nedra Pickler in Washington contributed to this report.
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