At one point, a reporter asked pointedly why the three-and-a-half years since the Affordable Care Act passed hadn't been enough time to build the site.
"I think when you look at the complexity of the system and all the pieces that were interrelated," Bataille said. "I think it is no surprise to anyone that we were operating under a compressed time frame in order to do the rigorous testing that was needed."
The website's performance has improved in the last few weeks, and more people have started to apply for coverage, she said. According to CMS, 700,000 people have begun applications, although Bataille did not provide a breakdown of how many came through the state-based marketplaces and how many came through HealthCare.gov, which covers 36 states.
About one-third of the website's visitors are looking only for information about the ACA, Bataille said, while the other two-thirds are actively looking to shop and sign up for coverage.
The administration is confident that people will be able to shop and sign up for coverage before Dec. 15, the deadline for enrolling in coverage that will start on Jan. 1, 2014, Bataille said.