But after a frantic push to repair HealthCare.gov began to bear fruit in December, enrollment dramatically increased.
However, in light of the crippled launch, the CBO in February revised its estimate for total enrollment the close of open enrollment to 6 million — 1 million below its original projection.
That benchmark was hit in late March with about a week to go before the official March 31 deadline. And right after that deadline, Obama announced that enrollment had topped 7.1 million.
That total grew in the past two weeks, as people who had started applications on the Obamacare exchanges took advantage of the deadline waiver.
The White House on Thursday did not disclose the number of enrollees who have paid their first month's premiums.
Republicans have suggested that the true enrollment tallies have been lower than announced because a certain percentage of enrollees have not, and will not, pay their first premiums.
Industry experts have said they expect that about 15 percent of enrollees won't make their first payments for a variety of reasons. Officials on California's exchange, which has the highest sign-up tally of any state, on Thursday said they have seen that same rate of non-payment for its enrollees.
If that rate holds up nationwide, it would mean that about 6.8 million people would end up being officially enrolled in Obamacare plans.
Rep. Fed Upton (R-MI) chairman of the House Energy and Commerce Committee, wasn't swayed by Obama's call for Republicans to drop their efforts to repeal or signficantly weaken the Affordable Care Act.
"This law has disrupted health care for millions of Americans, sent premiums skyrocketing, limited access to doctors, and cancelled plans, and even after all of that havoc, its ability to add to the insurance rolls is based largely on the fact that it forced Americans to purchase government-mandated coverage under the threat of costly penalties from the IRS," Upton said in a prepared statement.
"The administration still has not answered basic questions about enrollment and why it will not support fairness for all."
But the president of Enroll America, a leading ACA advocacy group, said "we're thrilled" by the 8 million enrollee tally.
"The results speak for themselves: millions of Americans now have the affordable, quality health insurance they and their families deserve," said Anne Filipic, the Enroll America president.
Census changes to mask true Obamacare effect