

President Obama is doing a series of interviews to encourage enrollment, including one with WebMD and with "Between Two Ferns" with Zach Galifianakis. (Reuters/Funny or Die)

President Obama said Friday he was confident enough Americans had enrolled under the Affordable Care Act to make the program "stable."

In an interview with WebMD, Obama said the fact that 4.2 million people have already signed up for plans under federal and state marketplaces mean enough companies will be invested to stay in the system.

“Well, at this point, enough people are signing up that the Affordable Care Act is going to work. The insurance companies will continue to offer plans,” the president said. “It will be a larger number than that by the end of March 31st, the deadline to get insurance this year.”

Obama noted, however, that the larger question is whether the risk pool is diverse enough to ensure premiums don't skyrocket, since "the more you can spread the risk with more people, the better deal you’re going to get."

"You know, the impact in terms of the program has always been based more on the mix of people who sign up. Do we have a mix of people who are gray-haired like me and may have some old basketball injuries and aches and pains, along with young people who are healthy and don't really have any issues right now?" he asked. "Do we have a good mix of gender, in terms of men and women?"

The interview with WebMD was part of the White House's ongoing effort to reach targeted groups such as young people, or in this case women, who make up 60 percent of the Web site's visitors.

Even as he touted the virtues of the law, Obama acknowledged that some previously-uninsured Americans may not be able to see the providers they want if they were focused on keeping costs down.

"But for the average person, many folks don’t have insurance initially, they’re going to have to make some choices. And they may have to switch doctors, in part because they’re saving money," he said. "But that’s true if your employer suddenly decides, ‘We think this network going to give a better deal, we think this will help keep premiums lower, you’ve got to use this doctor as opposed to that one, or this hospital as opposed to that one.’"

"The good news is, in most states, people have more than one option. And what they’ll find, I think, is their doctor or network or hospital that’s conveniently located is probably in one of those networks," Obama added. "Now, you may found out that network is more expensive than another network, and maybe you’ve got to make a choice about what’s right for your family."

A White House official noted that the federal law now requires an adequate network of providers, and in the coming year Health and Human Services "plans to have even more aggressive efforts in place to ensure that consumers have good networks of doctors, community providers and specialists."