Correction: A previous version of this article suggested that immigrants who are legal U.S. residents must wait five years before buying health insurance on the new online marketplaces. That restriction is for people joining Medicaid. This version has been corrected.

California has surged ahead in implementing the federal health-care law, but it is lagging in one way that could have major implications for the program’s success: Latinos appear to make up only a small fraction of those who have signed up.

The numbers have prompted concern because so many of the state’s uninsured are Hispanic, and it could be a sign that enrollment efforts targeted toward Latinos are behind nationwide as well.

Hispanics are a linchpin of the health-care law because they constitute more than a third of the estimated 29 million people who are eligible to buy coverage on the online insurance exchanges. The population skews young, making Latinos an important demographic for the Obama administration, which is seeking to keep premiums low by coaxing healthy people to join the insurance pools.

Even though the administration has not released national Hispanic enrollment numbers, the California figures are a “red flag” for what might be happening more broadly, said Gabriel R. Sanchez, a pollster specializing in the Hispanic community and head of the Robert Wood Johnson Center for Health Policy at the University of New Mexico.

“California was supposed to be out in front of the pack on marketing efforts targeting Latinos,” he said. “The fact that their numbers don’t look good is pretty dire for the administration.”

Less than 5 percent of the 109,296 people who enrolled in health insurance in California in October and November identified themselves as Spanish speakers, according to data released by the state on Thursday — a strikingly low number considering that more than a quarter of the state’s population primarily speaks Spanish and that Latinos constitute nearly half the number of uninsured who are eligible to buy coverage on the state exchange.

Although the figure does not reflect the number of Latinos who registered in English, the 4,498 sign-ups among Spanish speakers were significantly less than the 6,453 enrollments among speakers of Asian and Pacific Islander languages — a group that makes up about 10 percent of the state population, according to census data.

The state has seen an aggressive $86 million promotional push devoted to boosting enrollment among Californians of all stripes, including Latinos.

“What the heck was that money for? I’m very frustrated by what I see as a poor job to implement the promise of the Affordable Care Act,” said state Sen. Norma Torres, a Democrat who represents a heavily Hispanic part of Los Angeles County. “We have to do better.”

Administration officials say it is premature to be raising alarm bells about Hispanic enrollment, because people have until March 31 to sign up and they expect December enrollments to be much higher than the previous two months.

A big promotional push by the White House aimed at Latinos won’t start until January. Numbers specifying how many Hispanics have enrolled have not been released.

“Our expectation was always that the number of enrollees, including Latino consumers, would be low in the first months, but we expect enrollment to increase over time,” Katherine Vargas, a White House spokeswoman, said in a statement.

But the technical problems that beset the federal marketplace,, was a major setback. The administration was forced to cancel a “Hispanic Week of Action” that was planned for late October. The Spanish-language version of,, became active only last weekend even though it was scheduled to launch with the English site on Oct. 1.

One problem identified by workers helping Hispanics sign up for coverage across the country is the confusing process for submitting applications from people whose families include U.S. citizens as well as legal and illegal immigrants.

Under the law, illegal immigrants may not buy coverage through the exchanges. They may purchase insurance for the U.S. citizens in their families, as well as any legal residents, but advocates say the process has been difficult.

The system asks for the applicant’s Social Security number as many as three separate times, even though it is not required if applicants are not seeking coverage for themselves. The system uses a person’s credit history to verify his or her identity, but many illegal immigrants lack such a history.

Moreover, because people with complex family situations must complete more steps to finish their applications, the system has more opportunities to crash.

“It’s clear that many of the systems are not equipped to handle complex processes or to assist speakers of other languages, so our message right now [to Latinos trying to sign up for coverage] is that they need to understand they’re going to face barriers and they are going to face frustrations but that it is very important that they sign up,” said Jennifer Ng’andu, health policy director for the National Council of La Raza, a Hispanic advocacy group.

Another problem has plagued U.S. citizens born in other countries. The marketplaces require people to submit something called a “naturalization certificate number,” which was assigned to them when they attained citizenship, for some people many years or decades ago.

The request sent Juan Carlos Perez digging through his old paperwork in his garage in Pasadena, Calif., to produce a number he was given at age 14 and hasn’t had to use since.

“It was one of those moments where I was reminded I am not an equal citizen,” said Perez, 43, a freelance writer who was born in Peru. “It just felt very alienating, and a reminder that you’re not quite fully accepted. It was not something I expected to see on this site.”

The Hispanic community looks more positively on the health-care law than Americans overall, with 44 percent offering the program a favorable rating and 27 percent viewing it unfavorably in a recent Kaiser Family Foundation poll. By contrast, about half of all Americans in the survey said they dislike the law.

Latinos are also happier than the general public with the implementation of the legislation, with 51 percent approving of President Obama’s handling of the rollout in Washington Post-ABC News polling this fall, compared with 37 percent of the public overall.

But that may not translate into large numbers of uninsured Latinos enrolling. In a recent Harvard University poll of the “millennial” generation, only 30 percent of Hispanics younger than 30 said they would buy insurance on the exchanges if they were eligible. Another third said they are “50-50,” and another third said they would not.

California’s difficulties do not bode well for what is happening in two other states with large Latino populations: Florida and Texas. Leaders in those states have resisted the law, translating to fewer resources for groups on the ground trying to get people to sign up for health plans.

California, by contrast, has embraced the law and set up its own marketplace. But the Spanish-language version of California’s site fell short of expectations. There were basic spelling errors — for example, spelling “sí,” the Spanish word for “yes,” as “si,” the word for “if.” At some point during the enrollment process, the Web site switched to English. There have been long waits for people trying to get a Spanish speaker on the state’s hotline.

Santiago Lucero, a spokesman for Covered California, said the numbers were better than they were in October but not where they need to be. He blamed the initial difficulties partly on an early lack of Spanish-speaking enrollment counselors, a problem that is being addressed.

Some workers nationwide see evidence that interest among Latinos is increasing with the Dec. 23 deadline approaching for people to enroll in coverage that starts Jan. 1.

Laura Leon, project manager for the Sinai Health System in Chicago, said hundreds of people attended an enrollment fair last weekend despite frigid temperatures. Interest was so strong, she said, that when people showed up at a wrong address that was printed in a local newspaper, they arranged for carpools and vans to get everyone to the right location.

“Right now we are seeing so many people, they are asking can there be an extension,” Leon said. “We don’t know how we are going to fulfill the demand.”

Scott Clement contributed to this report.