"Thanks to the Affordable Care Act, 20 million Americans have gained health-care coverage," said Sylvia Burwell, the secretary of the U.S. Health and Human Services Department.
"We have seen progress in the last six years that the country has sought for generations. Americans with insurance through the health insurance marketplace or through their employers have benefited from better coverage and a reduction in the growth in health-care costs."
Obama announced the new tally during a speech in Milwaukee, where he touted the benefits of the ACA, and where he was introduced by a Wisconsin man named Brent Brown, who had written a letter to the president that said "you saved my life" by getting the law passed.
Brown's letter noted that he had not voted for Obama, and that he was an ardent Republican who had previously been "very vocal in my opposition to you — particularly the ACA.
"I am so very sorry," Brown wrote. "I was so very wrong."
"I have a 'pre-existing condition' and so could never purchase health insurance," Brown wrote. "Only after the ACA came into being could I be covered."
"I would not be alive without access to care I received due to your law."
Last September, officials estimated that 17.6 million people had gained insurance because of Obamacare. The latest estimate of 20 million people reflects increased enrollment in health coverage programs, such as in 2016 health plans sold on Obamacare exchanges during open enrollment, which ended Jan. 31.
The new tally relates only to coverage gains for adults ages 18 to 64. Officials said that if children and people 65 years old are not considered, the uninsured rate is estimated to be 11.5 percent.
But officials noted that the separate National Health Interview Survey, which looks at total U.S. population, for the first nine months of 2015 has estimated that the overall uninsured rate is just 9.1 percent.