President Obama announced Thursday that 8 million people have successfully signed up for healthcare through the Affordable Care Act's online marketplace.

"Eight million people," Obama said. "Thirty-five percent of people who enroll through the federal market place are under the age of 35. All told, independent experts now estimate that millions of Americans who were uninsured have gained coverage this year."  

Thanks to last minute sign-ups, especially in California, the 8 million sign-ups beats forecasts by 1 million. The remarkable number of sign-ups comes after a poor rollout of the website in the fall.

At the beginning of April, about 7.1 million had enrolled.

The health law has helped bring the largest increase in insurance coverage in the U.S. in half a century. 

"This thing is working," Obama said from the White House briefing room.

California announced Thursday that over 200,000 consumers signed up for coverage in the last two weeks. That brings California's number of sign-ups, the most in the nation, to almost 1.4 million people. 

In addition to those who signed up through the online marketplace, millions of others signed up through other means like Medicaid, through their employers or directly through insurance companies. This brings the nation's uninsured rate down to 12.9%.

Due to technical problems with the healthcare.gov website, the March 31 deadline to enroll in the online marketplace has been extended. Some states are still allowing individuals to enroll.

New Gallup survey data released this week says that nearly 12 million individuals who didn't have insurance last fall now do.

Obama has fiercely defended his healthcare law, that is often criticized by Republicans and said Democrats should be proud for their efforts. 

"I think Democrats should be forceful in their defense, he said. "There is a good story to tell." 

The future for the Affordable Care Act is unknown and it faces many obstacles, but with the 8 million who signed up online and possibly 4 million more who enrolled in another way, the present sure looks healthy.