Zients said almost daily fixes are already having an impact. For example, over 90 percent of users can now complete one of the first steps, creating an account.
But the application process, which involves submitting and verifying personal information and income details, remains "volatile," he said. At one point, as few as one-third of users were getting through that part.
Zients said there are two big categories of problems. Performance issues involve the speed and reliability of the website. Functional issues are bugs that keep the software from working as intended. He said the government has a "punch list" of needed fixes that adds up to dozens in each broad category.
Near the top of the list: insurers are getting enrollments with incomplete, incorrect or duplicative information.
Until now, officials at the federal government's Centers for Medicare and Medicaid Services have taken the lead operational role on HealthCare.gov. The government operates a successful e-commerce site for Medicare coverage, but it appears to have to have gotten in over its head when it comes to Obama's law. Maryland-based QSSI will now be responsible for the execution.
The company built a component of the website called the federal data hub that appears to be working relatively well. The hub is a conduit for verifying consumers' personal information with government agencies.
An executive of the parent company, Andrew Slavitt, told Congress this week that QSSI had concerns about the federal website and relayed those to the government. Officials said the company's new role as "general contractor" will be an expansion of its current contract.
Its parent company also owns UnitedHealthcare, the nation's largest provider of Medicare Advantage plans, a popular private insurance option available to seniors.
One of Obama's top campaign fundraisers was Anthony Welters, executive vice president of UnitedHealth Group. According to information from the nonpartisan Center for Responsive Politics, Welters ranked 31st among Obama's top "bundlers," raising more than $785,000 toward the president's 2012 campaign. Welters' wife, Beatrice, is the former ambassador to Trinidad and Tobago. She also raised money for Obama in 2008.
Associated Press writers Bree Fowler, Jack Gillum, Jim Kuhnhenn and Chris Tomlinson contributed to this report. Tomlinson reported from Austin.
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