A review of internal structural diagrams obtained by AP also revealed the complexity of the system. The diagrams show that applicants must submit at least 50 pieces of personal information, including income and immigration status. That data is then connected to at least eight distinct federal computer systems, including the Social Security Administration and the Peace Corps.
The schematics from late 2012 show how officials preferred a "data services hub" -- a traffic cop of sorts for managing information -- instead of a setup that would have allowed state exchanges to connect directly to government servers when verifying an applicant's information.
On Sunday, the Department of Health and Human Services said the data hub was working, but the initial consumer experience had not lived up to the public's expectations. "We are committed to doing better."
Administration officials have so far refused to say how many people have actually managed to enroll in insurance during the three weeks since the new marketplaces became available. Without enrollment numbers, it's impossible to know whether the program is on track to reach the projections from the Congressional Budget Office, which estimated 7 million people would gain coverage during the first year the exchanges were available.
Officials have instead pointed selectively to figures putting the insurance exchanges in a positive light. They say more than 19 million people have logged on to the federal website and nearly 500,000 have filled out applications for insurance through both the federal and state-run sites. The applications must be completed before people can enroll in insurance policies.
An internal memo obtained by the AP showed that the administration had projected nearly a half million people would actually enroll for the insurance markets during the first month.
Uninsured Americans have until about mid-February to sign up for coverage if they are to meet the law's requirement that they be insured by the end of March. If they don't, they will face a penalty.
Officials say that at this point they are not considering extending the enrollment window beyond that time. They also say they are not considering taking the website down for an extended time to address the problems, but instead will do that maintenance during low-traffic overnight hours.
But the White House appeared to open the door to not penalizing those whose efforts to sign up were confounded by the system's problems.
"The law is clear that if you do not have access to affordable health insurance, then you will not be asked to pay a penalty because you haven't purchased affordable health insurance," said White House spokesman Jay Carney.
So far, no one within the administration is known to have been fired for the problematic rollout. Some Republicans have focused their ire on Health and Human Services Secretary Kathleen Sebelius, though the White House says she continues to have the confidence of the president.
Sebelius is scheduled to testify about the botched rollout before the House Energy and Commerce Committee next week. Representatives from some of the contractors working on the websites were also scheduled to testify before the committee Thursday.
Associated Press writers Ricardo Alonso-Zaldivar, Luis Alonso and Laurie Kellman contributed to this report.