WASHINGTON (AP) The senior administration official whose agency oversaw the crippled "Obamacare" enrollment website apologized to Congress on Tuesday for the severe technical problems that marred the online rollout of President Barack Obama's health care overhaul, which she said were not acceptable.

Obama's White House legacy depends heavily on the success of his massive overhaul of the U.S. health care system, which has so far been a deep embarrassment. Members of the powerful House of Representatives Ways and Means committee were questioning the head of the agency tasked with launching the enrollment website that froze computer screens across America after its Oct. 1 debut.

"I want to apologize to you that the website has not worked as well as it should," Medicare chief Marilyn Tavenner said as she began her testimony before the panel. It was the most direct mea culpa yet from a top administration official.

When questioned, Tavenner also said she could not answer until next month how many Americans had been able to enroll under the new program.


Lawmakers were demanding explanations about what Tavenner knew about the shaky internet portal's problems and whom she warned before it opened for business nearly a month ago. They want to know what went wrong with HealthCare.gov, but also whether lawmakers can trust administration promises to that it will be running efficiently by the end of November.

The administration's bungled rollout of system that promises to provide coverage for millions of uninsured Americans has given an opening to embattled Republicans ahead of next year's congressional elections. The Republican strategy to shut down the government on the day the Obamacare website launched failed to force the president to delay or defund the overhaul and led to record low approval ratings for the party.

Against that backdrop and with the U.S. as deeply divided along partisan lines as at any time in recent history, the hearing quickly devolved into a resumption of Republican arguments against the whole program, not just the technical problems. House Republicans have tried to revoke or delay the new health care law at least 40 times since it was signed into law in 2010. Most Democrats, some also critical of the roll-out snags, were left to defend the program as a solution to America's longstanding health care troubles.

Republicans also said insurance companies are notifying policyholders who bought coverage privately that their plans were being canceled. That's a result of the portion of the overhaul law that requires coverage to meet certain standards. Americans hit by the cancellations are complaining that the cost of new coverage has risen significantly. Republicans hammered Tavenner to answer yes or no when they asked if Obama had not lied when he had insisted that the law would not require people to change coverage.

Tavenner acknowledged the initial website performance "has not lived up to the expectations of the American people and is not acceptable." But she also seconded administration talking points that despite the website problems the law is living up to its promise of quality, affordable health insurance for those who don't have access to employer-provided coverage, the way most Americans get health care.

Tavenner is less well known than Health and Human Services Secretary Kathleen Sebelius, who has been lampooned on late-night TV comedies and whose resignation has been demanded by some Republicans. Sebelius is likely to face some of the same questions Wednesday when she appears before another powerful House panel, the Energy and Commerce Committee.

Tavenner, however, was closer to the day-to-day work of setting up the enrollment website, which was handled by experts within her agency, the Centers for Medicare and Medicaid Services, along with outside contractors. The agency oversees the government programs that provide health care coverage for the elderly and poor, and critics question why it was given the task of launching the website instead of private contractors who have now taken the lead.

Like other administration officials, she previously had assured Congress that everything was on track for a reasonably smooth launch in all 50 states.

"If people can't navigate such a dysfunctional and overly complex system, is it fair for the IRS to impose tax penalties?" said Ways and Means Chairman Dave Camp. In a concession, the White House has said it will waive penalties for anyone who signs up by March 31, in effect granting a limited grace period.

With sign-up problems so widespread and persistent, even some Democrats have joined Republicans in calling for a one-year postponement of the law's new mandate that everyone must obtain health insurance or pay a tax penalty. The insurance industry warns that such a delay would saddle the new system with too many high-cost, older patients and too few healthy young people, whose participation is needed to fund the program.

The website was supposed to serve people who don't have a health insurance plan through their employer. Its target audience is not only uninsured Americans but the self-employed who already purchase coverage individually. A companion site for small businesses has also run into problems.

The U.S. has been the only major developed country without a national health care system, and the overhaul was supposed to change that. The system is not the centralized, government-run setup seen in places like Britain. Instead it uses various ways to require or encourage Americans to get private insurance or, for the poor or elderly, government-provided insurance.

Under the law, middle-class people can qualify for tax credits to make private health insurance more affordable, while low-income people will be steered to the established Medicaid program in states agreeing to accept federal money to expand it.

Some lawmakers also want assurances about the security of the HealthCare.gov site and unintended consequences from the feverish, hasty work to repair the site.


AP writers Ricardo Alonso-Zalvidar and Stephen Ohlemacher contributed to this report.