The man appointed by US President Barack Obama to overhaul a bungled health care website rollout said Sunday that it had undergone "night and day" improvements in handling online traffic.

The White House had admitted that the launch of, where people can sign up for health insurance, had been a debacle, but promised that the vast majority of potential customers would be able to enroll online by the end of November.

"The site now has the capacity to handle 50,000 concurrent or simultaneous users at one time ... so the site will support more than 800,000 consumer visits a day," said Jeffrey Zients, an Obama advisor recently appointed to troubleshoot and deliver solutions to those trying to fix the troubled website.

"We've doubled the system's capacity and can now support its intended volume," he said during a conference call with reporters.

Additionally, the website is running successfully 90 percent of the time, up from an estimated 42.9 percent through much of October.

Julie Bataille, communications director for the Centers for Medicare and Medicaid Services said that 80 percent of users are now able to apply for health insurance successfully on the site.'s rollout on October 1 sent Obama's approval rating tanking and pushed his fellow Democrats into open revolt at times and sparked an opening for gleeful Republicans opposed to the president's health reforms.

Only approximately 27,000 people were able to subscribe for insurance via in October, according to official figures.

Obama campaigned in 2008 on the promise of insuring some 30 million Americans who lacked health insurance.

"We developed a prioritized punch-list of software fixes, hardware upgrades and user enhancements with the prioritization based on what has the biggest impact on system stability, capacity, speed and user experience," Zients said.

Those improvements include implementation of a technical support center monitoring the website 24 hours a day and the elimination of more than 400 bugs.