Administration officials are vowing to have ObamaCare's enrollment site fully repaired by Nov. 30, a full two months after the site's disastrous debut.
"By the end of November, HealthCare.gov will work smoothly for the vast majority of users," said Zients, who was appointed earlier this week to oversee the repairs on a short-term basis.
"It will take a lot of work, and there are a lot of problems that need to be addressed, but HealthCare.gov is fixable," he said.
Friday's comments were the administration's most direct admission so far that system-wide problems are plaguing HealthCare.gov, the online enrollment portal serving 36 states.
They also represent the clearest disclosure of how federal officials plan to attack the issues over the next five weeks.
While emphasizing that the enrollment site does not need to be scrapped, Zients described working off an initial "punch list" that includes more than two dozen must-do repairs.
One high priority is fixing part of the system that is sending error-ridden application data to health insurers, Zients said, as well as improving the basic user experience.
As part of the triage effort, the Centers for Medicare and Medicaid Services (CMS) announced that it has appointed one of the companies behind HealthCare.gov as a "general contractor" for the repairs.
That company, QSSI, is behind the site's problematic account registration tool and its data hub, which officials said is functioning well.
Zients said the firm would pursue a "relentless focus on speed and execution to work through the punch list."
The CMS would not disclose how much QSSI's new role will cost, nor what other experts have been involved with the so-called "tech surge" to asses the site's problems.
The Nov. 30 deadline for repairs is the first timetable from the administration on when the system will function smoothly.
Applicants must enroll by Dec. 15 in order to receive healthcare plans that take effect on Jan. 1.
Though the enrollment period lasts until March, the White House is under serious pressure to fix the problems before they create a drag on applications.
The marketplaces — ObamaCare's central mechanism for offering coverage to the uninsured — will need a balanced risk pool of millions of patients in order to operate well.
The CMS said Thursday that nearly 700,000 applications have been filed in exchanges around the country since Oct. 1, and the agency clarified Friday that more than half came through marketplaces associated with HealthCare.gov.
It is not clear how many have resulted in enrollments, or how many were for Medicaid instead of the exchanges.
Zients said Friday that at one point this month, as few as three in 10 users were able to complete the application process.
"The bottom line is that the performance of the system has been unacceptable," he said.
"Now, we're executing a plan of attack and the system is getting better."
Federal health officials plan to release enrollment figures on a regular basis starting next month.