The site – the main portal for insurance marketplaces in 36 states – got 1.2 million visitors Tuesday and 1.1 million visitors Monday, according to the administration.
At the same time, call centers received more than 500,000 calls over those two days.
Despite the crush, the website, which crashed repeatedly last year, has been stable, said Kurt DelBene, a former
"Since the traffic started to climb, we have seen only minor issues, all of which have been addressed rapidly," DelBene said.
The surge in consumers comes as the administration is taking steps to ensure that Americans who start the enrollment process by Monday but fail to complete it will still be able to get health coverage.
The administration issued formal guidance Wednesday that indicated the federal government would provide consumers a "limited amount of additional time to finish the application and enrollment period." To qualify for the extension, consumers will only have to attest that they started the process before the deadline.
Julie Bataille, a spokeswoman for the Centers for Medicare and Medicaid Services, which is overseeing HealthCare.gov, would not specify how long consumers would have to complete the process.
But she said consumers who have not started the process by March 31 would have to wait to get coverage on the marketplace during the next open enrollment period, which starts in November.
After April 1, consumers who lose their job, get divorced or otherwise lose their insurance through a change in life circumstances will still be able to enroll in health coverage through the marketplace.
Other consumers also may be able to buy health insurance directly from insurance companies, but they would not qualify for subsidies that are available to consumers who make less than four times the federal poverty level, or about $94,000 for a family of four.
Americans who do not have coverage this year may be subject to a penalty of $95 per adult, or 1% of their income, whichever is greater, when they file their taxes next year.