Sebelius' forthright statement about her ultimate accountability for problems with the sign-up rollout came as Rep. Marsha Blackburn, R-Tenn., peppered her with questions about the "debacle."
"Hold me accountable for the debacle," Sebelius responded. "I'm responsible."
Rep. Henry Waxman of California, the ranking Democrat on the committee, scoffed at Republican "oversight" of a law they have repeatedly tried to repeal.
"I would urge my colleagues to stop hyperventilating," said Waxman. "The problems with HealthCare.gov are unfortunate and we should investigate them, but they will be fixed. And then every American will have, finally have, access to affordable health insurance."
The website HealthCare.gov was intended to be the online gateway to coverage for millions of uninsured Americans, as well those who already purchase their policies individually. Many people in the latter group will have to get new insurance next year, because their policies do not meet the standards of the new law.
Throughout the 3 ½-hour hearing, Sebelius was respectful, often addressing lawmakers as "sir" or "congresswoman." She kept her cool as some lawmakers repeatedly cut off her answers. But she did not shy a few times from tersely interjecting her views while a member was speaking.
The standing-room-only hearing room was silent when she swore an oath to tell the truth and began her opening statement.
Addressing consumers who've tangled with the confusing system, Sebelius added, "So let me say directly to these Americans, you deserve better. I apologize."
She parried questions about problems with the website as well as a wave of cancellation notices hitting individuals and small businesses who buy their own insurance. Those notices are coming because many existing individual policies are too skimpy to meet the law's requirements. The administration says consumers affected will be able to find better coverage.