Affordable Care Act signups are accelerating with two weeks left in open enrollment before uninsured people face a tax penalty.

After reporting 4.2 million signups through March 1, the exchanges now have signed up more than 5 million, thanks to “a weekend wave of consumers.”

Marilyn Tavenner, the administrator for the Centers for Medicare & Medicaid Services, made the announcement in a blog post Monday.

“The last several days have been the busiest since December, with the Call Center taking more than 198,000 calls on Thursday alone — the busiest day since December 23 — and more than 130,000 calls over the weekend. Last week, HealthCare.gov saw more than 4 million visits — and an additional 1 million visits this weekend,” she said.

“With only two weeks to go, we’re continuing to work hard to ensure that every American who wants to enroll in affordable coverage by the deadline of March 31st is able to do so. So don’t delay; tell your friends and family to sign up today,” she said.

The boost for the administration comes amid a massive marketing effort by the White House and its allies to make up for lost ground from the disastrous first two months of the rollout of the national health care website — and several of the state-run websites as well.

The Congressional Budget Office has projected that 6 million will sign up — down from its initial projection of 7 million.