One of the lead contractors responsible for developing the government’s troubled healthcare website said on 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 January 1.

Andrew Slavitt, executive vice president with the parent of Quality Software Services Inc, said his company told the Centers for Medicare and Medicaid Services of concerns about testing the 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 healthcare policy, commonly called “Obamacare.”

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 December 15 deadline to obtain benefits beginning on January 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.

The troubled rollout of the online exchanges, or marketplaces, is undergoing its first full-length public airing on Thursday in a crowded congressional hearing room, where lawmakers questioned technology contractors.

Lawmakers are trying to determine why the online portal for uninsured Americans in 36 states has malfunctioned since its October 1 start, the beginning of a six-month enrollment period that is expected to draw at least 7 million people to sign up for federally subsidized private insurance for 2014.

Republicans who control the panel criticized top administration officials and contractors for assuring lawmakers over the summer that the system would work, only to produce an enrollment characterized by crashes, glitches and system failures.

“This is not about blame – this is about accountability, transparency, and fairness for the American public. The broken promises are many,” said Representative 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,” Upton said.

The Department of Health and Human Services and the White House have largely declined to disclose information about the problems plaguing the system, which cost nearly $400 million to build, according to a report by the watchdog Government Accountability Office.

Democrats dismissed the Republican rhetoric as partisan politics, saying the committee’s goal should be to “fix, not nix” the 2010 Patient Protection and Affordable Care Act, Obama’s biggest domestic policy achievement.

“The Affordable Care Act is an enormous success with one obvious exception: it has a poorly designed website,” said Representative Henry Waxman, the lead Democrat on the panel.