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The finger-pointing was in full swing Thursday at a tense Capitol Hill hearing where the contractors behind the botched ObamaCare website defended their work and claimed the government failed to properly test the system before launch.

The contractors faced tough questioning from lawmakers on both sides of the aisle, who voiced frustration with the weeks-long problems surrounding the federal hub. Lawmakers cast doubt on attempts by contractors, who were paid millions, to claim they were not responsible for many of the site's problems. Top contractor CGI Federal revealed it was paid $290 million in taxpayer funds.

But CGI Federal and other contractors repeatedly claimed that overall "end-to-end" testing was the responsibility of an agency within the Department of Health and Human Services, as was the decision to go live on Oct. 1.

They suggested more time was needed to work out the -- major -- kinks.

Representing contractor QSSI, Andrew Slavitt told the committee that ideally, end-to-end testing should have occurred well before the launch, with enough time to correct flaws.

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    "Months would be nice," said Slavitt.

    "We would have loved to have months," concurred CGI vice president Cheryl Campbell, though she earlier claimed no amount of testing could have flagged all the problems.

    Questioned whether there were concerns the site was not ready to go live, she also said: "It was not our position to tell our client whether they should go live or not go live."

    Slavitt said his firm did share concerns with the agency, Centers for Medicare & Medicaid Services, adding they were responsible for addressing them.

    "We identified errors in code that was provided to us by others," he said. "In this function we reported back the results to CMS and the relevant contractor, who in turn was responsible for fixing coding errors or making any necessary changes."

    He also blamed in part a "late decision" to require customers to register before browsing for insurance, which could have helped overwhelm the registration system.

    "This may have driven higher simultaneous usage of the registration system that wouldn't have otherwise occurred if consumers could window-shop anonymously," he said.

    CMS officials, in a conference call later in the day, acknowledged that there should have been more testing, but said there wasn't due to the "compressed" timeframe. They also claimed responsibility for the decision to make people fully log on before browsing for insurance.

    The hearing before the House Energy and Commerce Committee was the first of what is likely to be many on the failures of the main ObamaCare website. Health and Human Services Secretary Kathleen Sebelius, who skipped Thursday's hearing for an event in Phoenix, is expected to testify next Wednesday.

    While Sebelius will face tough questioning, lawmakers on Thursday also took issue with much of the contractors' testimony, as they assigned blame to CMS and each other.

    Rep. Anna Eshoo, D-Calif., questioned their claims that "unexpected volumes" of traffic caused much of the trouble.

    "I think it's really kind of a lame excuse," she said. "Amazon and eBay don't crash the week before Christmas and ProFlowers doesn't crash on Valentine's Day."

    The witnesses at times downplayed the problems with the site itself, prompting jeers from lawmakers.

    "The system is working. People are enrolling," Campbell testified, acknowledging the system is still too slow.

    Noting that the administration is urging people to use paper applications, Rep. Joe Barton, R-Texas, said: "That is a system that has failed."

    Campbell -- who said she still thinks everything will be fixed in time for the Jan. 1 hard launch -- and others acknowledged the system needs to be improved. But all four contractor representatives tried to spread the blame around for the problems to date. Representatives from Equifax Workforce Solutions and Serco also spoke.

    Campbell said QSSI's tool that allowed consumers to create secure accounts created a "bottleneck" in the system.

    Slavitt later said QSSI takes "accountability" for the problems with that function.

    Lawmakers from both sides of the aisle took aim Thursday at the contractors, even as they implicated administration officials. Lawmakers were indignant as they complained that officials looked them in the eye before Oct. 1 and told them the launch of HealthCare.gov was on track.

    "Either these officials were shockingly unaware of what was happening ... or deliberately misleading our committee and the public," Rep. Tim Murphy, R-Pa., said.

    "They said there was nothing wrong, and they expressed nothing but optimism," Rep. Diana DeGette, D-Colo., said.

    Republicans, still committed to repealing Obama's health care law, approached the questioning with a prosecutorial tone, leading New Jersey Democrat Frank Pallone to call the whole exercise a "monkey court."

    An official with the Department of Health and Human Services plans to brief House Republicans on the site on Oct. 30.

    The Associated Press contributed to this report.