The president pointed to benefits already available under the 3-year-old health care law, including ending discrimination against children with pre-existing conditions and permission to keep young people on their parents' insurance plans until they turn 26.
But he conceded the troubled launch of the open enrollment period that began Oct. 1.
"There's no excuse for it," he said. "And I take full responsibility for making sure it gets fixed ASAP. We are working overtime to improve it every day."
Underscoring the president's challenge, the healthcare.gov website was down, because of technical difficulties, during his remarks.
Obama also tried to clarify the most recent controversy surrounding the law — the wave of cancellation notices hitting small businesses and individuals who buy their own insurance. When he was trying to sell the health care overhaul bill to the public, Obama had vowed that anyone who liked their insurance would be able to keep it.