While the site's navigability is improving each week, analysts fear there are deeper problems lurking within the system.
Health insurance companies have reported receiving jumbled and half-empty applications for coverage as a result of technical glitches.
ObamaCare critics fear that premium tax credits will go to people who are not technically eligible because of problems with the system.
These and other concerns will be the topic at Congress's first hearing on the ObamaCare rollout since Oct. 1.
Republicans on the House Energy and Commerce Committee are ready to grill federal health officials about the rollout next Thursday — if any decide to show up.
The panel asked Health and Human Services Secretary Kathleen SebeliusKathleen SebeliusObama's health secretary to be first female president of American University Leaked email: Podesta pushed Tom Steyer for Obama’s Cabinet Romney: Trump victory 'very possible' MORE to testify, but she has declined so far.
Energy and Commerce Committee Chairman Fred Upton (R-Mich.) slammed the secretary in a statement last week, noting that she recently appeared on Comedy Central to promote ObamaCare.
"This is wholly unacceptable," Upton said. "Secretary Sebelius had time for [‘The Daily Show’ host] Jon Stewart, and we expect her to have time for Congress."
The panel is planning to focus on when administration officials knew that the rollout would be rocky.
Republicans have accused Sebelius and her deputies of obscuring details about ObamaCare's problems in past testimony.
Lawmakers are also likely to inquire about how many people have signed up for coverage on the exchanges so far.
The administration has said it will not disclose initial enrollment figures until November.