U.S. Health and Human Services Secretary Kathleen Sebelius, in her third congressional hearing since the disastrous October 1 rollout of the website at the center of President Barack Obama's policy overhaul, sought to reassure lawmakers that steps were being taken to find out what went wrong and to install a stronger management team.

U.S. officials reported on Wednesday that about 365,000 people signed up for healthcare coverage in October and November through the federal HealthCare.gov website and online portals to 14 other marketplaces operated by individual states. The online shopping sites for insurance plans were established under the 2010 Patient Protection and Affordable Care Act, commonly called Obamacare.

Republicans questioned the veracity of the numbers. At a congressional hearing, Representative John Shimkus of Illinois took issue because Sebelius could not say whether those who signed up through the marketplaces had secured their enrollment by paying their first month's premiums.

"When Amazon.com records a book sold, they record a book sold based on someone who has paid for it, not what is in their shopping cart, not what is on their wishlist," Shimkus said at a hearing of the House Energy and Commerce health subcommittee. "So our concern is this 365,000 figure is fraudulent because it is not those who have purchased plans yet."

CHANGING THE MESSAGE

Sebelius testified that interest in the subsidized coverage provided under the law had grown to 5 million visitors who logged onto a revamped HealthCare.gov during the first week of December alone. Officials are expecting a surge in enrollment before a December 23 deadline for people to sign up for coverage that starts at the beginning of next year.

Enrollment appeared to be far off track of a forecast from the nonpartisan Congressional Budget Office that 7 million people would sign up in Obamacare plans by March 31. The administration has said it does not have specific targets for enrollment in the first year.

Hours before the start of Wednesday's hearing, Sebelius announced in a blog posting that she had asked her department's inspector general to investigate the performance of private contractors in the flawed debut of HealthCare.gov.

She also acknowledged in testimony that in retrospect she would have opted for a soft launch on October 1 that would have made the website available to a limited number of users through beta testing.

Republicans on Wednesday also keyed in on worries that problems with the "back end" of the federal government's technology system could snarl enrollments for some consumers who signed up for coverage.

"Far too many Americans who were happy and satisfied with their healthcare coverage on January 1st of this year have had the worlds turned upside down," said Representative Fred Upton of Michigan, who chairs the House Energy and Commerce Committee.

Democrats on the panel defended Sebelius by accusing Republicans of harboring an insincere interest in public insurance woes and exaggerating the law's flaws.

"I don't know where the reality is on their part. Sometimes I think they're living on Mars rather than Earth," said Representative Frank Pallone of New Jersey, the subcommittee's top Democrat.