Health and Human Services Secretary Kathleen Sebelius said enrollments on are surging but confirmed that the administration is still millions short of its target of signing up 3.3 million Americans by the end of December.

In testimony before an Energy and Commerce subcommittee Wednesday, Sebelius said improvements to the website have helped 258,497 Americans sign up for coverage under Obamacare through the end of November, bringing the total for the two months to nearly 365,000.

“As more Americans give a second look, they're finding the experience is night and day compared to where we were back in October,” she said in an opening statement. “And they're responding by shopping for plans and enrolling in greater numbers.”

Rep. Joe Pitts, R-Pa., who chairs the panel's health subcommittee, asked Sebelius to confirm his estimate that those sign-up numbers are nearly 3 million short of the administration's original goal for the first three months of online enrollment.

“Through the end of November, that is correct, sir,” Sebelius responded.

For the law to operate properly, the administration needs to sign up a total of 7 million people in the exchanges by March 31, the deadline for 2014 enrollment.

Rep. Fred Upton, R-Mich., who chairs the full Energy and Commerce Committee, though said the net numbers tell a far grimmer story.

Upton argued that more than 5 million Americans have lost their coverage because of new Obamacare regulations that are forcing insurers to stop offering many current plans. Even if the administration achieves its best-case scenario, “millions more Americans would have lost coverage than gained it in the first months of the rollout,” he said.

Ahead of the hearing Wednesday morning, Sebelius announced that she was asking her department's inspector general to investigate the “structural and managerial policies” that led to the flawed launch of

She also called on Centers for Medicare and Medicaid Services Administrator Marilyn Tavenner to create and fill a new post for a CMS chief risk officer.

“I will instruct this office to look at IT and contracting and the risk factors that impeded” the successful launch and “how we can mitigate risk as we move forward,” Sebelius said, noting that the officer would look into improving the federal government's contractor and procurement management.

Under questioning from Rep. Marsha Blackburn, R-Tenn., Sebelius said that the administration has “obligated $677 million” for IT costs associated with the rollout and fixes and had already spent $319 million of that total as of October.

Blackburn also pressed Sebelius over the timing of two key Obamacare delays. The day before the July Fourth holiday the administration announced that it would delay for a year a requirement that larger businesses offer insurance to their workers. Another set back came the day before Thanksgiving when the administration announced that the online small-business exchange would be delayed for a year.

“What new delays will be coming on Christmas Eve and New Year's?” Blackburn asked.

Sebelius did not rule out further delays, saying only, “We're working with insurers to make sure there is a smooth transition in the new year.”

Senior Democrats on the panel came to the defense of both Sebelius and the Affordable Care Act.

Rep. Frank Pallone, D-N.J., mocked GOP criticisms of the law and its rollout.

“I don't know where the reality is on their part,” he said. “Sometimes I think that they're living on Mars rather than earth.”

Pallone said he held a health care forum in his district Monday night and heard “just the opposite” of GOP concerns. He said people were happy that they were able to enroll and many of them were able to obtain coverage for the first time.

“It just boggles my mind to hear these Republican comments about a world turned upside down when the reality is that the Affordable Care Act is working. People are getting affordable insurance with good benefits. I mean, that's the reality that I hear when I'm home, and I'm not making it up.”

Aside from the website's problems, the law and President Obama's poll numbers have taken a beating over his broken promise that Americans could keep their current insurance plans. Hundreds of thousands of people with individual insurance plans have received cancellation notices over the last few months but the actual number of cancellations resulting from the new law is difficult to pin down.

Rep. Henry Waxman, D-Calif., who spearheaded the effort to pass the law through the House, said he was encouraged by the new numbers showing a surge in enrollment over the past few weeks.

He blamed conservative groups for spending millions of dollars trying to “demonize” the law and sharply disputed Upton's contention that more people have lost their coverage than gained it in the the first three months of enrollment.

“That absolutely cannot be true and is not true,” he said, citing Congressional Budget Office predictions that 7 million Americans would enroll in Obamacare during the first year.

He said Republicans are exaggerating the numbers of cancellations by including people who have had a change in their policy as losing coverage, as well as young people who are opting to stay on their parents’ policies until age 26.

“Republicans are saying, 'Oh see, they're losing that policy,'” he said. “Well, that doesn't make sense – unless you're trying to exaggerate the numbers.”

Sebelius and Democrats had an even tougher time defending another broken Obamacare promise – that Americans will be able to keep the doctors they have. Millions of doctors are not participating in the exchange system.

In the state of New Hampshire, for instance, only one insurer is participating in the federal exchange: Anthem Blue Cross and Blue Shield. Anthem recently barred 10 of the state's 26 hospitals from its health plan on the exchange, meaning those who have signed up may be forced to travel over an hour to see a doctor.

Given these reports, along with similar stories around the country, Rep. Renee Ellmers, R-N.C., asked Sebelius whether she still stands by Obama's promise that Americans could keep their doctors under the new law.

Sebelius said insurers have always made decisions “day in and day out” to change which doctors they offer in their plans.

“As you well know, in the private market, networks change on a constant basis,” she said. “There is nothing in the law that has their doctor lost to them.”

Republicans also questioned Sebelius on reports that consumers in 41 states and D.C. can expect an average premium increase of 41 percent by switching from their previous plan to those offered on the exchange.

Obama, in pitching the law, has repeatedly said an average family would save more than $2,000 on their premiums.

“Would you agree today that this simply is not true,” Pitts asked Sebelius.

While Sebelius sidestepped any discussion of premium costs, she said overall that the rate of increase for health care costs has gone down since the law passed in 2010.

“Underlying health costs are rising at the slowest rate in 50 years,” she said. “So Americans are seeing a very different cost trajectory than they would have absent the passage.”

This story was published at 11:52 a.m. and has been updated.