The website -- Healthcare.gov -- has crashed repeatedly since it went online Oct. 1, with the Obama administration saying it has had 17 million unique hits.
A U.S. operation of the Canadian company CGI has so far had the most involvement in setting up the website, receiving a contract in October 2011, when it estimated a cost of $94 million. As of May, the cost had risen to $292 million.
Ontario fired CGI in 2012, canceling a $46 million contract and alleging the company missed a deadline for establishing an online medical registry. CGI told NBC News it is negotiating a resolution to the issue, but has declined comment for weeks on the healthcare.gov rollout.
Federal officials said the cost increase was due in part to more states signing up to participate in what is commonly called Obamacare, NBC said.
White House press secretary Jay Carney said Thursday "the glitches are unacceptable" but he said Americans are getting health insurance."
Republican National Committee Chairman Reince Priebus is demanding Health and Human Services Secretary Kathleen Sebelius resign and the House Energy and Commerce Committee has scheduled a hearing for next week on the ACA rollout.
Technology experts said construction of the site was using 10-year-old technology, USA Today reported.
NBC said Friday the Spanish enrollment tool of Healthcare.gov -- which had been planned for next week -- has been delayed indefinitely, although Spanish speakers can enroll by telephone.