Washington (CNN) -- Call it the Obamacare website fiasco, with the focus Wednesday on Health and Human Services Secretary Kathleen Sebelius after she told CNN that President Barack Obama knew nothing of the problem before it became evident starting on October 1.
Sebelius headed to the White House for an afternoon meeting with insurance industry executives, then was scheduled to leave town to participate with other officials in what the administration calls a "grass-roots effort" to boost enrollment in Obama's signature health care reform system.
Republican opponents seeking to undermine the 2010 Affordable Care Act call for Sebelius to be fired for the website problems in the program overseen by her department.
They also want to delay the deadline for people to obtain health coverage under the law or face a fine, with some congressional Democrats joining that call.
Here are the latest developments:
Insurance CEOs meet with officials
The CEOs of several major insurance companies -- including the heads of Aetna, WellPoint and Humana -- met Wednesday with top U.S. officials about problems with the Obamacare website's rollout.
White House Chief of Staff Denis McDonough and Health Secretary Kathleen Sebelius led "a very productive discussion" that ended with an agreement that technical groups from insurers will work directly with government experts to address the issues, said a source in the room.
"The reality is that we have so much expertise they haven't tapped into enough," said the source. "These are people who have built these systems."
A well-placed industry insider told CNN that top health insurers were well aware of problems with the website's application process ahead of its October 1 launch, yet people involved in its creation downplayed the flaws.
"It's clear the folks working on this, in the (Obama) administration, gave a far rosier picture to people in the White House," the insider said. "No one wanted to go to the White House and say to the President that your significant legislative achievement may not go well."
The troubles include the difficulties that many people are having setting up accounts, as well as the fact that enrollment files being received by insurers are sometimes incomplete, have erroneous information or arrive in duplicate.
At the same time, some people have managed to successfully enroll, though the insider couldn't put an exact count on how many.
Fixing the problems
At the White House, spokesman Jay Carney gave reporters the most detailed account yet of steps being taken to address the website problems that have included long delays, difficulties signing in and incorrect information getting relayed to insurance companies.
"We are making fixes to the existing system," Carney said, noting that developers were increasing the bandwidth and "improving site architecture" to deal with the volume of visitors to HealthCare.gov.
"We're substituting in hardware to make changes that make it more optimized," Carney added. "And we're improving database queries."
More tests are coming "now that we know what we're dealing with in terms of volume," he said.
Carney also said the Department of Health and Human Services will hold daily briefings, starting Thursday, to provide updates on progress being made to improve the website, one of four ways for people to enroll in the insurance exchanges set up under Obamacare. The others are by phone, in person at sites set up across the country, and by mail.
Signing up the uninsured
Sebelius and other Cabinet secretaries as well as White House officials will head to cities across the country to encourage uninsured people to enroll in the new system.
"We are planning to deploy White House officials and Cabinet secretaries to the 10 cities across the country with the highest rates of uninsured Americans to do enrollment events and other grass-roots activities," an administration official said. "These cities and metropolitan areas include Dallas, Houston, Miami, Atlanta, Phoenix/Tucson, North Jersey, Tampa, Orlando, Detroit and San Antonio."
Exclusive CNN interview
In the interview Tuesday with CNN's Dr. Sanjay Gupta, Sebelius said Obama didn't hear that there might be problems with the sign-up portal for new exchanges under the health care law until it went live on October 1.
The site was supposed to make it simple for people to search and sign up for new health care policies, but instead it has been clunky and, at times, inoperable.
She attributed some problems to "extremely high" volume, saying nearly 20 million people came to the HealthCare.gov website in the first three weeks after its launch.
Of those, about 500,000 created accounts on the website, far below the millions that the administration hopes to eventually sign up in the six-month open enrollment period that ends on March 31.
Administration officials also note that such sign-ups traditionally start slow as consumers shop around, with the most activity occurring in the final weeks and days before the final deadline.
Carney said Obama knew there would be "glitches" and said ahead of time there would be problems in the rollout, but "there is no question that we did not anticipate the scale of problems with the website."
Republicans said the Sebelius interview showed the President didn't know what was going on with the law nicknamed for him.
Republican National Committee Chairman Reince Priebus issued a sharply worded statement on the latest development.
"Either Secretary Sebelius is lying to protect President Obama or the President needs to get control of his signature health care law," he said.
Sebelius said she is bringing in tech experts from Silicon Valley, as well as acting Office of Management Budget Director Jeff Zients, to try to fix website problems that have included long delays, the inability to enroll and bad information relayed to insurers.
Asked why the leading experts were only getting involved now, instead of before the website launch, Sebelius said of the contractors and agencies responsible for the project: "We (had) hoped that they had their 'A-Team' on the table" from the start.
For now, she said, "we want new eyes and ears," adding that "we want to make sure that we get all the questions on the table, that we get all the answers and accelerate the fix as quickly as possible."
Republicans already are challenging the concept, calling it a "money surge" and seeking information from some of the outside experts about what they are supposed to do.
In letters Wednesday to five technology companies -- Verizon Enterprise Inc., Google, Microsoft, Oracle and Expedia -- House Oversight and Government Reform Committee Chairman Darrell Issa of California asked for details of what involvement, if any, they have in the surge.
"Despite the President's assertion that 'we're well into a tech surge,' neither the White House nor (the Department of Health and Human Services) is providing additional details about which private sector companies have been engaged or whether they are being engaged through the appropriate procurement processes," Issa said.
His letters asked the companies for all their communications with the agencies involved in the health care reform effort as well as with the Office of Management and Budget and Obama's executive office.
At least two committees in the GOP-led House have scheduled hearings this week and next to investigage the rollout problems.
"Clearly there's problems with the website, but I would argue that the problems go much further than that," House Speaker John Boehner told reporters on Wednesday.
Officials from the contractors hired to create the website, including CGI, Serco, and Equifax, will appear on Thursday before the House Energy and Commerce Committee, with Sebelius scheduled to testify at another panel hearing next week.
Meanwhile, the House Ways and Means Committee has a hearing set for next week with the head of the Centers for Medicaid and Medicare Services, a division of the Health and Human Services department that oversees Obamacare reforms.
One question certain to come up is why the rollout wasn't postponed after warnings in prelaunch tests that the website would fail. Sebelius told CNN that further delaying health coverage for Americans who need it was not an option.
"There are people in this country who have waited for decades for affordable health coverage for themselves and their families," she said.
Meanwhile, administration officials will brief House Democrats about the health care law's implementation on Wednesday, which caused their Republican counterparts to demand their own briefing. There was no immediate word on a separate session for the GOP.
A third committee sent a letter to the 11 HealthCare.gov contractors requesting documents, meeting lists, and all communications with the Obama administration on the project. The House Oversight and Government Reform Committee gave the firms two days to respond.
Delay of game
Conservative Republicans who forced the 16-day government shutdown by linking a funding measure to demands to dismantle or defund Obamacare now want to delay the creation of market exchanges -- a key component of the reforms.
The Obamacare exchanges create large pools of buyers to make coverage more affordable for the almost 50 million Americans without insurance.
Robust enrollment is vital to the program's success. The exchange effort also depends heavily on attracting younger, healthier participants, who would tax the health care system less but still pay premiums. That would help insurers offer lower rates to older Americans with more health care needs.
If younger people don't sign up, rates won't increase immediately but It could cause insurers to raise them in the future or drop out of the exchanges because they cannot make the economics work.
Carney said GOP calls to delay the individual mandate that requires people to obtain health coverage lacked "a sincere desire to improve the system" and instead were intended to undermine Obamacare.
However, some congressional Democrats -- especially those facing tough election battles next year -- are getting restless about the Obamacare problems.
Democratic Sens. Jeanne Shaheen of New Hampshire, Mark Begich of Alaska and Mark Pryor of Arkansas called for extending the enrollment period, while Rep. John Barrow of Georgia wants to delay the individual mandate.
The Obamacare exchanges are expected to include about 15% of Americans, with the rest of the insured population covered by employer or other group plans.
Republicans, including House Budget Chairman Paul Ryan of Wisconsin, also call for Sebelius to lose her job over the rollout problems.
Some Democrats also call for accountability, but they say the situation should first get fixed before assessing blame and firing anyone responsible.
Sebelius said she works "at the pleasure of the President" and is committed to her job.
"I think my job is to get this fully implemented and to get the website working right," she told Gupta.
CNNMoney's Jennifer Liberto and CNN's Jim Costa, Bryan Koenig, Jim Acosta, Deirdre Walsh, Paul Steinhauser, Greg Botelho and Adam Aigner-Treworgy contributed to this report.