The Web site. (Jon Elswick/AP)

The Obama administration said Sunday that it had met its goal of improving the online health-insurance marketplace so that it works well for the vast majority of users but acknowledged it still has extensive work to do to buttress a troubled Web site that has marred the rollout of President Obama’s signature health-care initiative.

After a series of technical fixes and capacity upgrades, many of which were made over the past week, is now working more than 90 percent of the time — a big improvement over October, when the site was operating only about 43 percent of the time and frequently crashed, said Jeffrey Zients, the administration official overseeing the improvements.

“Bottom line, on December 1st is night and day from where it was on October 1st,” when the site was launched, Zients said in a teleconference with reporters Sunday morning.

Even with the improved performance, some people are likely to encounter problems on the site. And there is another worry — reports sent to insurance companies about who has enrolled in health plans include errors that could cause problems when people try to use their new insurance plans next year.

Administration officials, in talking to reporters, were careful not to declare a full-fledged victory. In a report issued Sunday, officials with the Department of Health and Human Services said the next few months would require further work to “improve and enhance the website and continue to improve the consumer experience.” Officials have also said repeatedly that consumers might still encounter difficulties and urged them to use the call center and seek help from specially trained personnel.

A look at the consumer's route through the website and the potential failure points.

Still, the announcement is a milestone for the administration, which has struggled to improve the Web site since its botched Oct. 1 launch.

New challenges lie ahead. Most Americans are required to have health insurance starting Jan. 1, and the administration is racing to meet its now-tougher goal of enrolling 7 million uninsured people in health coverage by the end of March.

When the Web site launched, the uninsured, as well as people who were looking for better or cheaper coverage, were supposed to be able to go online to browse plans and rates, apply for subsidies and enroll in health plans. But many have encountered numerous technical difficulties on, the main portal for 36 states, as well as on a number of state-run Web sites.

Fixing the federal Web site was a crucial first step for the administration to restore trust in the health program, which has suffered in the polls this fall. It was also critical from a practical standpoint; people buying insurance on the marketplaces have until Dec. 23 to sign up for health plans that take effect on Jan. 1.

It may be hard to assess how well the site has met expectations until it handles a higher volume of visitors as Dec. 23 approaches.

The announcement offered some relief to Democratic lawmakers, who have struggled to defend the administration’s handling of the law.

“This is the equivalent of having a great item that you want to buy in the store but not being able to get through the front door,” Sen. Robert Menendez (D-N.J.) said Sunday on CBS’s “Face the Nation.” “It sounds like the front door has been opened successfully now.”

Republicans said additional flaws in the site would soon emerge.

“When this Web site gets fixed, the problems really start for this administration,” former senator Rick Santorum of Pennsylvania said on CNN’s “State of the Union.”

Zients, on his call with reporters, said the number of people on the site was higher Saturday than it had been for all but the first days after the exchange launched.

Among those who tried to log on was Sandy Kush, 49, an unemployed medical transcriptionist from Illinois who tried six times in October to use, with no success.

She tried again Sunday and, with the help of a call-center representative, was able to enroll in Medicaid — a stopgap measure, she said, until she can find a new job that offers insurance. The whole experience took about an hour and a half but “was pretty smooth,” she said.

Others reported problems getting all the way through the process. Liz Gallops, 33, a North Carolina insurance broker who has tried unsuccessfully to get coverage through the site, said that seemed to be working better Sunday but that at one point she got a message stating that the system “cannot finish your application now.”

In the HHS report, ad­ministration officials offered a harsh assessment of the project and blamed the problems on hundreds of software bugs and inadequate hardware and infrastructure, as well as poor leadership.

“The system monitoring and response mechanisms were not sufficient for identifying issues or bugs or responding to them in real time,” it said. “Inadequate management oversight and coordination among technical teams prevented real-time decision making and efficient responses to address the issues with the site.”

But the officials said they had reorganized over the past five weeks and had put one firm in charge of the fixes, held “war room” meetings on critical issues and changed the decision-
making culture so their team is “operating with private-sector velocity and effectiveness.”

Zients said workers made more than 400 bug fixes and upgraded the software used for the enrollment process. The results are additional capacity, a faster response time and much-improved stability on the Web site, he said. About 50 fixes were made Saturday night, Zients said.

“We have a much more stable system that’s reliably open for business,” he said. “ can now support intended volumes.”

The HHS report concluded that most of the department’s benchmarks for this weekend had been met. The average system response time when a person calls up a page on the Web site is under one second and the rate at which people are encountering error messages is “consistently well below 1 percent,” the report said,

The online system is stable — not crashing — more than 90 percent of the time, officials said. And the report said that the site can handle as many as 50,000 shoppers at the same time and up to 800,000 visits a day.

The report said the administration has yet to meet at least one of its key goals: reducing the site’s average response time to half a second. And government officials, who spoke on the condition of anonymity to discuss ongoing operations, cautioned last week that they will not know if they have expanded the site’s carrying capacity to 50,000 users at once until they have that many users online.

Administration officials said they have set up a system to help consumers if they cannot immediately get access to the site during peak demand. If consumers visit the site when it is at capacity, they may leave an e-mail address to receive a notification from the site with a link that allows them to “go to the front of the queue when they come back to the site,” Zients said.

During the daytime Sunday, the site did not attract anywhere near the maximum number of users that HHS officials say should now be able to handle. The peak usage per hour came about noon, when 16,259 people were on the site at once, according to a government official with knowledge of the project.

Meanwhile, throughout the day Sunday, the site was meeting the administration’s target of an error rate of less than 1 percent, the official said, but the speed at which pages were loaded was roughly one per second, double the goal of a half-second.

The report did not address the “back-end” parts of the systems that consumers do not see, including the error-filled enrollment reports. Insurers have warned that if the problem is not fixed soon, some people may show up for doctor’s appointments in January only to find that the insurance company has no record of their enrollment.

“Insurers are still receiving enrollment files that are duplicative or include missing or inaccurate information,” Robert Zirkelbach, spokesman for America’s Health Insurance Plans, the industry’s main lobbying group, said Sunday. “In some cases they aren’t receiving those enrollment files at all.”

In recent months, consumers having difficulty with the Web site have been turning to agents and brokers for help. But the system does not allow brokers to enter their identity numbers once a person has gotten a subsidy determination, or if the number has been added incorrectly in the past.

Without those identity numbers, brokers cannot get paid by insurers or follow up on behalf of clients if there are problems with insurance claims. Regulators cannot track down brokers if there are mistakes. As of Sunday, brokers had not been informed of any fix to this issue.

Repairing those problems is critical because “we could get a lot of people enrolled very quickly,” said Janet Trautwein, chief executive of the National Association of Health Underwriters, which represents about 200,000 agents and brokers who together serve about 2 million to 3 million clients.

In addition, when consumers turn for help to a broker, an insurer or a call center, the online system still is balking at the critical step of calculating how much each person can qualify for in federal subsidies. Without that information, these assisters cannot complete the process of enrolling most consumers for health plans.

Emily Wax-Thibodeaux, Sarah Kliff, Juliet Eilperin, Amy Goldstein and Sean Sullivan contributed to this report.