That means more than 2.9 million signups are required for December to catch up to the original target pace, an ambitious goal even assuming a better-functioning website, a stepped-up outreach effort and lot of Americans waiting until the last minute to decide on a plan.

The Congressional Budget Office had projected that 7 million Americans would enroll by the end of open enrollment March 31.

Many health care writers have noted that the total number of enrollments is less important than whether the exchanges have a critical mass of younger and healthier participants to offset the cost of older and sicker enrollees. Though this is true, it’s also true that the lower the overall enrollment number, the less likely it is that the exchanges will have enough healthy participants to support a wide variety of plans.

HHS has not provided a demographic breakdown of those who have selected a plan.