A further 940,000 Americans registered for President Barack Obama's health care plans in February, bringing to 4.2 million the number of people who have signed up so far, officials said Tuesday.
The White House also geared up for what it said would be a "surge of enrollment" for the system, now that a malfunctioning website that hampered the law's rollout has been fixed, before a March 31 sign-up deadline.
"As more Americans are learning just how affordable marketplace plans can be, more are signing up to get coverage," said Health and Human Services (HHS) Secretary Kathleen Sebelius.
The new figures were unveiled on a day that comedy website "Funny or Die" debuted a new online video of the president braving the satirical jabs of comedian Zach Galifianakis, to market the plan to the site's young fans.
For the system to work, Obamacare must attract young, healthy registrants who do not make claims for big budget care in order to subsidize older, sicker patients who have also signed up.
The administration said 25 percent of those who signed up in February were aged between 18 and 34.
Officials believe that many more younger patients will be spurred to sign up before the deadline.
Americans who do not have health insurance by the end of the month are liable for fines under the new law, which is the centerpiece of Obama's domestic legacy and gets the United States closer to universal health care coverage than ever before.
The non-partisan Congressional Budget Office last month revised down its projected enrollment figures at the end of the six-month sign up period to six million from seven million.
Even that figure however may be now out or reach.
Officials declined to say whether they expected to reach the six million mark.
They also were unable to provide figures for the number of Americans who have paid for plans once enrolled and also could not provide a figure for the number of people who have signed up for coverage who previously had health care.
The latter figure will be crucial in establishing whether Obamacare, which inflicted a heavy political price on the administration, has actually achieved its goal of offering affordable healthcare to all Americans.
'Too little, too late'
Republicans, who have campaigned for years to repeal the law, charge that it is a failure. They point out that the president has delayed several key aspects of it and charge that modifications were meant to protect Democrats from damage in mid-term elections in November.
"It seems the president's push to enroll young adults is far too little, too late," said Brendan Buck, a spokesman for Republican House Speaker John Boehner.
"The administration won't tell us how many people have actually paid for a plan or how many were previously uninsured.
"But what we do know is that young adults—those who the White House repeatedly said are critical—are deciding the health care law is a bad deal."
Obama's appearance on the "Between Two Ferns" show in which host and "Hangover" star Galifianakis grills showbiz luminaries was an attempt to reach those crucial, younger Americans.
"What's it like to be the last black president?" Galifianakis asked Obama.
"What's it like for this to be the last time you ever talk to a president?" Obama hit back.
Galifianakis, spoofing low-budget television interview shows, also jabbed Obama over "ambassador" Dennis Rodman's trips to North Korea and ribbed him over his "home country" of Kenya.
Obama, a slick political performer, had his dead pan delivery down pat, and showed some sharp comic timing—though the show seemed more scripted than previous episodes featuring Hollywood stars like Natalie Portman and Charlize Theron.
"You can get affordable health care," Obama said.
"Most young Americans right now, they are not covered. They can get covered for what it costs to pay their cell phone bill," Obama said.
Explore further: More than 3.3 mln signed up to Obamacare health plans