(CNN) -- Health and Human Services Secretary Kathleen Sebelius strongly apologized for the botched launch of the government's Obamacare website before a congressional panel Wednesday.
She promised that a "vast majority" of consumers will be able to shop online for health insurance under Obamacare by the end of November without the problems currently being reported, even as the website was down once again.
"In these early weeks, access to HealthCare.gov has been a miserably frustrating experience for way too many Americans, including many who have waited years, in some cases their entire lives, for the security of health insurance," Sebelius said in her opening remarks before the House Energy and Commerce Committee.
"I am as frustrated and angry as anyone with the flawed launch of HealthCare.gov," she said. So let me say directly to these Americans: You deserve better. I apologize. I'm accountable to you for fixing these problems."
However, Sebelius said Obamacare has delivered on its central promise to provide affordable health care.
Thousands of people have been able to access the website to look at new health coverage options, she said.
She echoed the same stance the administration has taken -- that a team of experts is scrambling to fix the errors.
Pressed as to whether the Obama administration lied when it said that those who liked their current insurance policy would be able to keep it, Sebelius said the President kept his promise.
People who bought their own health coverage before Obamacare was signed into law in 2010 can keep those policies if they choose under a "grandfather" clause included in the legislation, she said. Those who like their health care plan can keep it, relying on the technicality that the coverage must predate the law, she said.
Sebelius was responding to a question about people having their policies canceled.
She said the troubled Obamacare website has cost $174 million so far, including $56 million for technological support.
Earlier congressional questioning
Invited to testify last week, Sebelius put it off for travel related to efforts promoting enrollment in new health insurance exchanges under Obama's signature domestic policy achievement.
One of her lieutenants -- Marilyn Tavenner, who heads the Centers for Medicare and Medicaid Services unit that oversees the HealthCare.gov website -- became the first government official to face congressional questioning on Tuesday at a House Ways and Means Committee hearing full of fiery partisan clashes.
Tavenner: Sorry for problems, but system working
Tavenner offered the first administration apology for the delays, error messages and other problems faced by Americans who have tried to sign up for health insurance on the website for the past four weeks.
5 things we learned from Tuesday's hearing
But she also insisted the online troubles were being resolved and the overall program was working, albeit slower and less successfully than hoped.
CNN has learned the administration was given stark warnings just one month before that the federal healthcare site was not ready to go live, according to a confidential report.
The caution, from the main contractor CGI, warned of a number of open risks and issues for the HealthCare.gov web site even as company executives were testifying publicly that the project had achieved key milestones.
Administration warned about Obamacare website
CGI had no comment other than to authenticate the report.
Brian Cook, a CMS spokesman, said the report was "not a dire warning" but more of a "list of things to do" if read in full, adding that "we worked to address those issues and all issues identified."
'Will be fixed'
The "vast majority" of consumers would be able to successfully use the site by the end of November, Tavenner said, telling millions of Americans that "I want to apologize to you that the website does not work as well as it should" and that HealthCare.gov "can and will be fixed."
Tuesday's hearing served as both a hot seat for Tavenner, whose agency has been blamed for the website troubles causing a political headache for Obama and the reforms passed by Democrats and upheld last year by the Supreme Court, as well as a venting session for Republicans after their failed efforts to scuttle the reforms.
More trouble for Obama came out of the testimony, as Tavenner conceded that some people with individual health coverage -- rather than the group coverage from employers that most Americans have -- will be forced to get new policies because of increased requirements under the 2010 Affordable Care Act.
Keep your plan? Maybe not
Some insurers changed or discontinued plans that failed to meet the Obamacare requirements, Tavenner said, even though present coverage could still be offered in some cases under a "grandfather" provision in the legislation.
She emphasized the individual health market involved "a small group" that had no protections before the Affordable Care Act.
Until now, such consumers "could be kicked out any time for pre-existing conditions" or realize too late that their policies failed to cover hospitalization or cancer treatments, Tavenner said. The reforms protect them by requiring a minimum standard of coverage, she added.
3 states tell insurers to scrap plans that don't comply with Obamacare
For some, that means more expensive policies, while any change in their coverage breaks the oft-repeated pledge by Obama that "if you like your plan, you can keep your plan" when he was pushing for Congress to pass the measure.
Opinion: Canceled health plan is a good thing
Republican Rep. Aaron Shock of Illinois hammered Tavenner on that point, noting a constituent who got a letter telling her that the health care reforms caused the cancellation of her current plan with a more expensive alternative in its place.
"She has health insurance that she likes. She's been paying her premium. She wants to keep it. But she can't," Shock said. "Isn't that a lie?"
According to the Kaiser Family Foundation website, 15.4 million people had individual health care coverage in 2011, representing about 5% of the population. The vast majority of Americans -- at least two-thirds of the population in 2011 -- had coverage through their employer, Medicare, Medicaid or other public providers and will not be affected by changes involving individual coverage.
At the White House, spokesman Jay Carney said "a significant portion" of the 5% of people with individual coverage will end up paying less for better policies when they shop around in the new exchanges.
"One of the issues that the Affordable Care Act was designed to address was the need to provide greater security to those Americans forced to seek insurance on the individual market," Carney said.
On Capitol Hill, a top House Democrat told reporters on Tuesday that his party "should have been more precise" when making the pledge about people keeping coverage they liked.
"I think preciseness would have been better," said Rep. Steny Hoyer of Maryland, adding that promise was made to try to allay the fears of the majority of Americans who get health coverage from their employers or government programs such as Medicare and Medicaid.
At Tuesday's hearing, Republicans warned the website problems foreshadow deeper troubles such as higher premiums and government intrusion in future health coverage, while Democrats accused them of trying to kill reforms that benefit millions of Americans.
Under relentless GOP questioning, Tavenner said initial figures on how many people have enrolled so far for health coverage under the reforms won't be available until mid-November and were expected to be low.
Pointing out that the enrollment period runs through March, Tavenner said a similar dynamic occurred with implementation of the Massachusetts health care law, when people waited until the final deadline approached to sign up.
To GOP Rep. Dave Camp of Michigan, the committee chairman, low enrollment signals the failure of the health care reforms, which need young and less expensive people to sign up so insurers can offer affordable plans in markets that include older and more expensive people.
"I fear we can see a fundamental breakdown of the insurance market where premiums will skyrocket, pricing millions of Americans out of health care," he said.
Later, Republican Rep. Kevin Brady of Texas asked Tavenner for a guarantee that consumers will be able to obtain coverage required by the health care law before the deadline.
"What I can guarantee is that we have a system that is working. We are going to improve the speed of that system," she said before Brady interrupted her.
"Excuse me," he challenged. "You are saying the system right now is working?"
Tavenner didn't budge, responding: "I am saying it is working. It is just not working at the speed that we want and at the success rate that we want."
Democratic Rep. Bill Pascrell of New Jersey lambasted Republicans on the panel for choosing to pile on the website woes in their continuing attempt to dismantle Obamacare instead of working with Democrats to improve settled law.
Citing the political battle last decade over the Bush administration's Medicare prescription drug benefit opposed by Democrats, Pascrell noted "we lost the policy fight" then but chose to help make the program work instead of trying to discredit or undermine it.
Standing up and pointing at his GOP colleagues, Pascrell shouted: "How many of you stood up to do that? None. Zero. Zero."
In prepared testimony for the hearing, Tavenner said private contractors hired to create the website "have not met expectations."
Earlier: Contractors blame government for Obamacare website woes
Asked about that statement, she cited one of the contractors -- CGI Federal, which has a contract worth as much as $200 million for its work on the system.
Tavenner's agency oversaw the creation of the online health insurance marketplace that has taken so much heat.
She reports to Sebelius, who has come under fire for the problems that plagued the introduction of the enrollment website. Some congressional Republicans demand that Sebelius resign or get fired.
In an exclusive interview with CNN last week, Sebelius said Obama didn't know of the problems with the Affordable Care Act's website until after the troubled launch. This was despite the fact that insurance companies had been complaining and the site crashed during a pre-launch test run.
CNN's Joe Johns and Z. Byron Wolf contributed to this report.