Impeachment aside, health care has emerged as a dominant campaign issue for Democrats this presidential election season. The idea of better, cheaper health care is popular with primary voters. But the idea of eliminating private insurance and replacing it with a government-run system is less popular. Still, that's what Massachusetts Senator Elizabeth Warren is endorsing. And yesterday, she released her plan explaining how she intends to pay for it. NPR's Asma Khalid is with Warren on the campaign trail in Iowa.

ASMA KHALID, BYLINE: The first stop of the day for Elizabeth Warren was a rally at a high school in Vinton, a small town with a population around 5,000. Warren did not mention her "Medicare for All" plan in her speech. But the first question she got from the crowd, from Dee Patters, was about health care and specifically what would happen to people like her who depend on unusual lifesaving drugs.

DEE PATTERS: I wholeheartedly support universal health care. But I also worry about the transition and whether or not the continuity of care will be able to be there as we transition to "Medicare for All."

KHALID: Warren told the crowd that her goal is to improve health care.

ELIZABETH WARREN: No insurance company in the middle to say, sorry, that doctor is out of network. No insurance company in the middle to say, I'm sorry, we don't authorize that treatment.

KHALID: And her plan, she says, would save middle-class families money.

WARREN: We should be an America where you get the health care that you need and that no one goes broke over it.

KHALID: I caught up with Patters after the rally. She told me she's not sure who she's going to caucus for - either Warren or California senator Kamala Harris. She gestured to her partner and explained that they don't think a public option being offered by some other candidates is enough. But she wants to hear more from Warren about how the country would transition to "Medicare for All."

PATTERS: We believe in universal health care, but it's that, you know, nagging, like, am I still going to be able to get everything I have now?

KHALID: Yesterday, Warren laid out an ambitious plan that explains how she would pay for "Medicare for All." It's a question she's been badgered with for months on the campaign trail and on the debate stage. Her plan calls for higher taxes on the wealthy, cuts to defense spending and diverting money to the government that employers already pay to insurance companies.

CHRIS VAN WAUS: I appreciate that she did lay out the information and details. I think that's good. It wasn't really necessary for me.

KHALID: That's Chris Van Waus, who was listening in the front row today with his daughter.

VAN WAUS: In the end, I think it's really a value judgment more than just purely a money judgment for me. Even if my taxes go up a little bit, I'm still supportive of "Medicare for All" because I think it's the right policy for America.

KHALID: Warren has insisted her plan will not increase taxes on the middle class. An NPR/PBS NewsHour/Marist poll found that a majority of Americans actually do not support eliminating private insurance in exchange for "Medicare for All," and that's what worries Mary O'Hearn.

MARY O'HEARN: I'm all about winning this time around. It's been a hard two and a half, three years.

KHALID: We met at a Biden rally the other day. She likes Warren. She thinks she's smart and good at explaining her ideas.

O'HEARN: But there's one thing about Elizabeth that I - I like if you like your health care, you can keep with that. That's the thing that I feel strongly about.

KHALID: How strongly could be key. It's not unusual to find voters who are uncertain about "Medicare for All" but like Warren as a candidate. The question is whether they'll stick with her.