By the end of March, there will be another moment of suspense: Can the Obamacare health insurance exchanges enroll enough people — or at least the right mix of people?

The open enrollment period for 2014 ends on March 31, so there could be another wave of last-minute signups. But the administration has been backing away from its early suggestions that 7 million people would be the goal for the exchanges — a number that came from the Congressional Budget Office estimate of how many people would enroll in the first year.

Instead, they’re now saying that even a smaller number would be fine, as long as there are enough young and healthy people to keep the health plans financially stable.

And even though it’s not clear yet whether that’s happening, they’re convinced that it will happen by the end of March, because they expect a big wave of people to sign up at the last minute — mostly people who didn’t have any reason to enroll earlier.

“We are focused on the long game for March 31,” said one White House official, because the experience of Massachusetts — which paved the way for Obamacare with its own health reform law in 2006 — “shows that people come in at the end.”