Politically, however, it will be a Republican field day, as it hands Republicans a fresh attack—one that undercuts Democrats' emerging success story of high enrollment—and could put vulnerable Democrats back on the defensive over a law they're trying not to talk about.
The Health and Human Services Department's latest update reported that 3.3 million people had selected an insurance policy on the law's new exchanges by the end of January. It was a positive report by almost any standard, and puts enrollment on track to hit 5 to 6 million by the time the window closes in March.
Democrats have touted the totals as a sign that the law is working, despite Republican intransigence and early technology disasters.
But if the early indications hold and the more accurate enrollment metric shaves 20 to 30 percent off the initial numbers, it will be a painful shift for Democrats. At current levels, it takes enrollment from 3.3 million down to about 2.6 million. If, hypothetically, 6 million people choose a plan by the end of March, real enrollment would be closer to 4.8 million.
That's enough for the new insurance markets to be sustainable, healthcare wonks say. The Affordable Care Act is already here to stay.
Still, the day the White House cuts its own enrollment totals by 20 percent is probably not going to be a very fun day for vulnerable Democrats, who are already frustrated with the administration over the delays and technical headaches that have riddled the implementation effort.
Republicans are trying to keep the debate focused on Obamacare, and to paint the law as not living up to expectations. And a downward revision in enrollment—even one done in the name of more accurate data—will put the law further away from the initial target of enrolling 7 million people this year.
But there's no way around it for Democrats. Party strategists say the White House has to release the more accurate figures once it has them, and that the best strategy for vulnerable senators is simply to ride out another GOP attack.
"The White House has got to be as transparent as possible from here on out. The last thing they can afford to do is get tripped up," said Jim Manley, a Democratic strategist and former aide to Senate Majority Leader Harry Reid.
Democrats don't expect the enrollment revision to do long-term political damage. Signing up 4.8 million people instead of 6 million people is still signing up 4.8 million people, they argue.
"Overall, I know there is a constant search for less than good news in the Healthcare.gov arena, but if you look at the data reported, it is overwhelmingly positive, and the predictions of failure and doom and gloom that we saw—understandably, perhaps, given how rocky the start was in October and November—have all come to naught," White House press secretary Jay Carney said last week when asked about people who had not paid their premiums.