The federal agency responsible for HealthCare.gov refused to say Thursday whether top officials had warned Health and Human Services Secretary Kathleen Sebelius that last-minute testing had revealed problems before the site launched Oct. 1.
Conducting its first media conference call to provide updates on site fixes, the agency also brushed aside a question about whether a top technology official was directly responsible for the decision to prohibit window-shopping for insurance plans on the site before people applied.
(Read more: Sebelius: Working '24-7' to fix website)
A contractor on Thursday told a congressional committee that she believed Henry Chao, an official with the Centers for Medicare and Medicaid Services (CMS), had made that call. It has been blamed for contributing to significant slowdowns on the Obamacare marketplace.
A lack of thorough testing was also cited. Contractors said they would have preferred "months" of testing rather than the week or so they had before the debut of HealthCare.gov.
"We don't want to look back," CMS spokeswoman Julie Bataille said at the start of the conference call.
The agency wanted to concentrate on steps being taken to correct problems and on the fact that there are more than five months for people to enroll in Obamacare coverage, she said, adding that a "compressed time frame" to the launch date had precluded more extensive testing.
"The focus of our work is on what we want to do right," said Bataille, who also said she was confident the fixes would let people enroll for coverage beginning Jan. 1.
(Read more: Contractors vow quick fix of Obamacare Web problems)
But Sebelius will have a tougher time dismissing questions concerning what and when she knew about prelaunch issues when she testifies before Congress next week. Republicans hostile to the Affordable Care Act, or Obamacare, have been demanding answers to those questions.