Recognizing that deeper problems may lurk behind the botched rollout of the health care website, President Barack Obama's top health official Wednesday called for an investigation into management and contracting decisions.

Health and Human Services Secretary Kathleen Sebelius said in a blog post early Wednesday that she is asking the department's inspector general to investigate the contracting process, management, performance and payment issues that may have contributed to the flawed launch of HealthCare.gov.

The website was supposed to have been the online portal to coverage under the new health care law, but technical problems turned it into a frustrating bottleneck for millions of consumers. It's working better now after two months of repairs.

The announcement comes as Sebelius heads to Capitol Hill for another round of grilling Wednesday before the House Energy and Commerce Committee. Lawmakers want explanations for dozens of questions about the website's design, workability and security. They also want to know why Sebelius and other top officials repeatedly assured them everything was on track.

"I believe strongly in the need for accountability, and in the importance of being good stewards of taxpayer dollars," Sebelius said in her announcement. The website has cost taxpayers more than $600 million so far, according to the congressional Government Accountability Office.