GWEN IFILL: The health law was the subject of a rare public conversation between President Obama and former President Clinton today.They sat down together at the Clinton Global Initiative, where President Obama referred to the showdown in Washington and responded to Republican opposition.

PRESIDENT BARACK OBAMA: Part of what I think the resistance that we have seen ramp up, particularly over the last couple of months, is all about is, the opponents of health care reform know they're going to sign up.In fact, one of the major opponents, when asked, well, why is it that you would potentially shut down the government at this point just to block Obamacare, he basically fessed up. He said, well, once consumers get hooked on having health insurance and subsidies, then they won't want to give it up.

PRESIDENT OBAMA: Now, that's -- I mean, you can look at the transcript. This is one of the major opponents of health care reform. It is an odd logic. Essentially, they're saying people will like this thing too much, and then it will be really hard to roll back.

GWEN IFILL: Beyond the politics, both presidents spoke at length today about one key aspect of the law, what it will mean for young adults, whose enrollment is critical to its potential success.That's our focus tonight as part of our ongoing series in which we try to answer viewer questions about the law.

Mary Agnes Carey of Kaiser Health News joins us. Kaiser Health News is an editorially independent organization focusing on health policy.Welcome.

MARY AGNES CAREY, Kaiser Health News: Thank you for having me.

GWEN IFILL: We're going to get right to the questions. The first is a video question actually that weget from a student. Let's look.

MEGHAN SHERWOOD, Missouri: Hi. I'm Meghan Sherwood, and I'm from Willard, Missouri.I was wondering how it would affect me -- I'm going into college in the next year -- and after college.

GWEN IFILL: That's a good question. What happens to college students who see their future maybe shrinking?

MARY AGNES CAREY: Well, it's a great question.In college, she could certainly stay on her parents' health insurance plan until age 26. The Affordable Care Act allows that to happen. I would check out her student health plan. What does that offer? Is that of interest to her? And also, after college, she could certainly stay on her parents' health insurance plan if that were a better deal for her. Her newemployer might actually offer her coverage.There will be a catastrophic option for people up to age 30, pretty high deductible, about $6,400, minimal coverage. And then she could look at the subsidies and the online exchanges that are part of the health care law.

GWEN IFILL: There's been a lot of discussion about what happens to people who can stay on their parents' health care plan until they're 26.Let's take a question from someone, Vickie in Concord, North Carolina, who wants to know what happens. She's actually an adult over 26 who has no income and has not filed an income tax return is year and is not a dependent of anyone else. Are they eligible, she wants to know, for subsidy and the like through the federal exchange?

MARY AGNES CAREY: My first thought when I heard about this situation is, what about the Medicaid expansion, if her state is expanding Medicaid? That -- the federal health law allows individuals up to about $16,000 of income. She says she hasn't -- doesn't have any income and hasn't filed a tax return inyears. Would that be a better option than looking at the exchange?

GWEN IFILL: Would it?

MARY AGNES CAREY: Well, chances are that Medicaid would offer more affordable coverage for her. She could certainly, depending on her income level, even she says she has no income -- the exchanges are open to people over 100 percent of income, but it could be a better deal for her,Medicaid, cover more than -- and at a better -- more affordable to her than if she went and did the exchanges.

GWEN IFILL: It sounds like people don't even recognize that Medicaid would still be there as part of this.

MARY AGNES CAREY: Well, it's difficult because some states are participating and some states are not.

GWEN IFILL: OK.Well, let's go on now to another young person, who is 26 years old, who says that she's single, a freelance photographer, makes about $6,000 a year. She says: "I still live with my parents. I'm from deep south Texas, where income levels are very low. I currently don't have any form of health insurance and don't understand how it works. What options will I have to access affordable health care?"

MARY AGNES CAREY: MThis is a complicated question, because her state is not expanding Medicaid.

GWEN IFILL: Exactly what we were just talking about.

MARY AGNES CAREY: Exactly what we were talking about. Her income is around $6,000 a year.The exchanges are open to people above 100 percent of the poverty line. That's about $11,500. So, in this case, Iwould recommend that she look at community health centers. They're all over the country. They have received additional money in the Affordable Care Act to do a variety of things, including providing more health care to individuals. And your pay is based on a sliding scale that would be based on her income.

GWEN IFILL: I have one more question for you, e-mail question from a viewer for you. And this is an interesting one.It's from a woman in Arizona, who writes: "I have a 25-year-old daughter with cerebral palsy who's presently covered by Arizona's version of Medicaid. Will Obamacare change her medical coverage? I also have a 27-year-old daughter who presently has no health insurance coverage. She is underemployed and makes just about poverty level income."Any advice for her?

MARY AGNES CAREY: For the younger child who is on Medicaid, you could not qualify her for a subsidy and go into the exchange, so she will stay in Medicaid. For older child, it sounds like she could qualify for a possible subsidy on the exchange to help with her premium, and also to get some help with co-pays and deductibles, because, as you remember -- as we remember, when you look at your health care expenditures, it's not just your premium. It's your co-pays and deductibles.But it sounds like the older child could get some help on the exchange possibly with both.

GWEN IFILL: Why is that people have these basic questions, do you think, at this point? Is it becauseit's just that complicated or is it that there just haven't been enough explanations offered?

MARY AGNES CAREY: It is just that complicated.But, also, I think people are very busy with their lives. They're working. Maybe they're taking care of their parents or their children. And now that the exchanges are going to open up on October the 1st, that really focuses people's attention. Will this be a good deal for he? Do I qualify? Can I get a subsidy? Can I get some assistance?I think it's kind of the natural course of things for people not to pay attention until they absolutely have to.

GWEN IFILL: Is it also possible that the political debate that Judy was just talking about has made people think this is not really the law?

MARY AGNES CAREY: I certainly think that could be part of the issue.When you hear that the House of Representatives has voted over 40 times to defund all or part of the law, you might not remember that it is, in fact, still the law of the land and is being implemented. So this is where the Obama administration really has to step up and explain the exchanges, the Medicaid expansion. They will be posting rates soon on the federally run exchanges. Many states have already made their rates there known.And so people need to really look at it and figure out what's the best deal for them.

GWEN IFILL: So, let's talk about what's actually law and what's actually real right now.Just for people who -- who get to stay on their parents' insurance until the age of 26, how many people has that affected since this actually became law?

MARY AGNES CAREY: As of December, according to the Department of Health and Human Services, about 3.1 million young adults, again, up to the age of 26 have stayed on their health insurance plan.It's oneof the more popular provisions of the law. It's been really a godsend for college graduates that maybe haven't found a job or haven't found a job that offers health care insurance.

GWEN IFILL: We know that three million have stayed on, but how many more are eligible to stay on? Do we know?

MARY AGNES CAREY: Well, the one thought of this is that the exchanges roll out, the government is really trying to aim enrollment at over three million young adults who are healthy -- they tend to be healthier -- to try to get them to get enrolled in health insurance, whether it's on their parents' planor on the exchanges, because, as we know, when you're younger and healthier, you balance out the risk of the older, sicker people.

GWEN IFILL: So everyone's just waiting to see whether this really stays real?

MARY AGNES CAREY: Right. And they have to just simply look at it to see what's the best thing for them.

GWEN IFILL: Mary Agnes Carey of Kaiser Health News, thanks for helping us out.

MARY AGNES CAREY: Sure. My pleasure.