A healthcare reform specialist helps people select insurance plans at the free Affordable Care Act (ACA) Enrollment Fair at Pasadena City College on November 19, 2013 in Pasadena, California. Many small insurers expected a bonanza of new customers when Healthcare.gov began on Oct. 1, but the website's problems made the first weeks very quiet for them. - 

A half-million people have signed up for insurance through the new federal healthcare exchange at healthcare.gov, President Obama said in his end-of-the-year news conference.

But what could be the site’s biggest test is still to come. Officials are bracing for a flood of traffic before Monday’s deadline to sign up for insurance that would begin in the new year.

“We increased the number of our call center staff by 50 employees,” says Carrie Banahan, head for the Kentucky Health Benefit Exchange. “We also extended our hours to Sunday.”

Banahan said enrollment numbers have jumped 40 percent since Thanksgiving, with 3,000 Kentuckians enrolling daily.  

There is such demand at times we just don’t have enough lines for individuals to call in,” she said. “They have to try back.”

When it comes to the federal exchange, officials say nearly 2 million people have applied and qualified for coverage. All that’s left for them to do is pick a plan, says Ron Pollack, of the healthcare advocacy group Families USA.

People obviously are taking time, and should take time to select a plan,” he said. “I think we are going to see people taking this last step in the next few days.”

What nobody knows is whether healthcare.gov can handle the wave of customers, and some have their doubts. Among them: Matthew Prince, who runs the firm CloudFlare, which builds websites and works with federal agencies on their site performance — though not on the federal exchange.

Given the challenges that the system had from the day it was launched, given the short amount of time that it has had before the deadline has come up, it’s likely that we will continue seeing challenges with the site going forward,” he says. 

Follow Dan Gorenstein at @dmgorenstein