One of the lead contractors responsible for developing the government's troubled health-care website said Thursday his company warned the Obama administration about rollout risks, while another expressed confidence that it will be fixed in time for benefits to go live on Jan. 1. Andrew Slavitt, executive vice president with the parent of Quality Software Services Inc. (QSSI), said his company told the Centers for Medicare and Medicaid Services of concerns about testing the Healthcare.gov website. ``We expressed all of those concerns and risks,'' Slavitt said in testimony to the House Energy and Commerce Committee, without immediately elaborating on what those concerns were. QSSI, a unit of United Health Group, was hired to build a "data hub'' that will allow people to buy insurance on the state exchanges that are the heart of President Barack Obama's signature health care policy. Another contractor, website developer CGI Federal, said the website will be fixed in time to allow people to enroll in private health insurance by a Dec. 15 deadline to obtain benefits beginning on Jan. 1. "The system is working. People are enrolling. But people will be able to enroll at a faster pace,'' said Cheryl Campbell, senior vice president at CGI Federal. CGI Federal built the federal website serving 36 states, and QSSI designed the part that verifies applicants' income and other personal details.

As the hearing began, Republican committee members said the website problems are symptomatic of deeper flaws in the Affordable Care Act, and they accused administration officials of misleading Congress with repeated assurances that the rollout was on track.

"This is not about blame—this is about accountability, transparency, and fairness for the American public. The broken promises are many,'' said Rep. Fred Upton, the Michigan Republican who chairs the committee "We still don't know the real picture as the administration appears allergic to transparency and continues to withhold enrollment figures.'' Democrats acknowledged the website problems but defended the law, saying millions of uninsured Americans are counting on it to finally get coverage—and thousands are succeeding in signing up. They accused Republicans of trying to sabotage the law, not to fix it.

"Republicans don't have clean hands coming here," said Rep. Frank Pallone, D-N.J. The hearing comes as President Barack Obama's allies are starting to fret about the political fallout. Democrats had hoped to run for re-election next year on the benefits of the health care law for millions of uninsured Americans. Instead, computer problems are keeping many consumers from signing up through new online markets. (Read more: White House IDs Obamacare site flaw) One House Democrat says the president needs to "man up" and fire somebody, while others are calling for signup deadlines to be extended and a reconsideration of the penalties individuals will face next year if they remain uninsured.

Senior vice president of CGI Federal Cheryl Campbell (L) talks to group executive vice president for Optum/QSSI Andrew Slavitt prior to a hearing on implementation of the Affordable Care Act before the House Energy and Commerce Committe Getty Images

On that point, a change in the timeline for signing up for coverage is underway, the White House said. Consumers have until Dec. 15 to apply for coverage that's effective Jan. 1. Even though open enrollment lasts until March 31, people would face a penalty if they postpone buying coverage beyond mid-February. Calling that a "disconnect," the White House said officials will soon issue policy guidance allowing consumers to sign up by the end of March without penalty. (Read more: White House to adjust health care penalty deadline guidance) The focus on the contractors is a first step for GOP investigators. After the failure of their drive to defund "Obamacare" by shutting down the government, they've been suddenly handed a new line of attack by the administration itself. Administration officials, including Health and Human Services Secretary Kathleen Sebelius, are to testify next week. Cheryl Campbell, senior vice president of CGI, suggested in prepared testimony that Congress should look beyond the contractors. HHS "serves the important role of systems integrator or `quarterback' on this project and is the ultimate responsible party for the end-to-end performance," she said. Overwhelming interest from consumers triggered the website problems, she said. "No amount of testing within reasonable time limits can adequately replicate a live environment of this nature," she said. Andy Slavitt, representing QSSI's parent company, said the operation's virtual back room, known as the federal data hub, is working well despite some bugs. But his company was also involved with another part of the system, a component for registering individual consumer accounts that became an online bottleneck. Slavitt blamed the administration, saying that a late decision to require consumers to create accounts before they could browse health plans contributed to the overload. "This may have driven higher simultaneous usage of the registration system that wouldn't have occurred if consumers could window-shop anonymously," he said. (Read more: )