Roughly 4 million people have signed up for health care plans through Obamacare's exchanges, the Obama administration announced late Tuesday.

Marilyn Tavenner, administrator of the Centers for Medicare & Medicaid Services, released the latest number of sign-ups in a blog post, arguing that President Obama's signature domestic achievement had reached a turning point.

“As we head into the last five weeks of this historic open enrollment period, millions of Americans are taking advantage of the new choices they now have to access affordable, quality health care thanks to the Affordable Care Act,” she said.

“The most recent data indicate that approximately 4 million people have now signed up for a private health insurance plan through the federal and state-based marketplaces since Oct. 1," Tavenner added. “A full enrollment report for February will be released in mid-March.”

The Obama administration released the figure with just a little more than a month before the March 31 deadline for individuals to obtain health insurance or pay a fine. The White House originally said that 7 million people would enroll in new health plans by that date, a goal that is very much in doubt in wake of the botched rollout of the website.

Two weeks ago, the Department of Health and Human Services said that 3.3 million people had signed up for Obamacare using federal and state exchanges -- an uptick in enrollment but still short of the pace needed for the administration to reach its original goal.

The administration trumpeted the 4 million figure as proof that Americans were increasingly receptive to the Affordable Care Act. However, the administration was unable to say how many people had actually paid for coverage or how many individuals were previously uninsured.

Republicans contend that most people now signing up for Obamacare already had health insurance. A recent survey from McKinsey & Co. estimated that just 11 percent of those enrolling in Obamacare plans were uninsured.

For Obamacare to succeed, the White House needs younger, healthier people to sign up in greater numbers to keep down premium costs for older, more sick patients.

The administration originally projected that 40 percent of all enrollments would come from the youngest demographic. But White House press secretary Jay Carney downplayed that benchmark on Tuesday, claiming that Obamacare could stay afloat even if 40 percent of enrollees weren’t from the youngest demographic.