The biggest domestic reform plan of Barack Obama’s presidency is facing its most important test.
Monday is the deadline to sign up for the Affordable Care Act, which will help the country's poorest citizens gain access to health insurance.
About 10 million people have signed up for private or government-run health insurance so far.
But for the programme to be fiscally sound, young, healthy people will also need to enrol.
The numbers show that 33 percent of those registering are within the key demographic, but experts say the number needs to be closer to 40 percent.
Al Jazeera's Patty Culhane reports.