As the battle between Hillary Clinton and Bernie Sanders over health care has heated up, a number of liberal writers have published pieces taking a hard look at Sanders’ single payer plan. The latest one comes from Jonathan Cohn, who concludes that, even if single payer is a desirable goal, the monumental scale of change that it would require — essentially wiping away the existing insurance structure and replacing it with a government plan that would squeeze providers to lower medical costs — renders it impossible for the foreseeable future.

As Cohn notes, Democrats couldn’t even get the public option passed back when they held Congressional majorities, and getting single payer would be infinitely harder; this raises further questions about whether Sanders is seriously grappling with the policy constraints the next Democratic president would face.

But the single payer flap suggests a line of questioning on health care for Hillary Clinton, too.

Clinton has repeatedly argued that, while she doesn’t think we should prioritize getting single payer right now, she remains fully on board with the broader ideal of universal health coverage. “I am absolutely committed to universal health care,” Clinton said at the last presidential debate. “We finally have a path to universal health care…I don’t to want see us start over again with a contentious debate. I want us to defend and build on the Affordable Care Act and improve it.”

And so, in Clinton’s telling, the argument is not over whether to strive for universal health care, but how to get there. (Her campaign has also misrepresented Sanders’ goals in some ways, but let’s put that aside for now and focus instead on this broader dispute over the best path to that stated goal.)

The fair question for Clinton is: How, in detail, would you go about building on the Affordable Care Act to cover the remaining uninsured?

Right now, an estimated 28.5 million people remain uninsured. I spoke today to Larry Levitt, a senior vice president at the Kaiser Family Foundation, and he suggested a number of policy ideas that could theoretically be adopted to help cover those remaining uninsured by building on Obamacare:

1) Further incentives for getting states to expand Medicaid. Levitt said that if the federal government were to offer to cover 100 percent of the costs of expanding Medicaid in the out years, that would “take away a key argument” that Republican governors have made for not expanding it. (The feds cover the full costs up front but the states pick up a small amount of the tab later.) Some 10 percent of the uninsured are estimated to be in that predicament because their states didn’t expand Medicaid. Clinton could talk in detail about other ways of getting reluctant states to opt in.

2) More and better outreach. Levitt notes that a key reason many remain uninsured is that those who do qualify for Medicaid, and reside in states that have expanded it, have simply not availed themselves of that option.  Levitt notes that the uninsured also include large numbers of low wage workers who are not availing themselves of employer based insurance that they’re eligible for. Clinton could address how she’d improve efforts to communicate existing options to these people.

3) Spending more money. Levitt notes that a lot of people who are eligible for ACA subsidies may still be facing prohibitively high costs. “It’s a legitimate argument that the coverage may not be affordable enough,” Levitt says, “so you might need additional subsidies to convince more of the remaining uninsured to buy insurance.” According to Kaiser, an estimated 22 percent of the uninsured are eligible for tax credits but not availing themselves of them.

Obviously calling for more spending might be politically difficult, but if Clinton’s goal is universal health care, she should be asked what this means — does she support taking politically difficult steps such as this one to get there? Are there other ways to bring down these costs? Clinton has talked about tax credits to help do that. “This is important, but it’s unclear how far it would go in expanding coverage,” Levitt says.

4) The public option. Brian Beutler explains how reviving the push for this is an obvious option for any Democratic candidate who says she wants to expand Obamacare coverage as meaningfully as Clinton’s rhetoric suggests she does. Even if this is hopeless in the near term, the broader point is that we need to know how Obamacare can be built upon in the near term.

Obviously this is a partial list, but it’s a starting point. In a sense, this battle has showcased what is supposed to happen in political competition, forcing the candidates into a substantive argument over health care policy that compelled Sanders to provide more details of his plan and subjected them to intense scrutiny. There’s no reason for the argument to end here, however.

“A single payer plan is not going to happen anytime soon, and the debate has obscured an important discussion about how to move beyond the ACA to cover more people and shore up insurance for those who already have it,” Levitt says.

If it is true that Clinton is being more realistic about the constraints the next Democratic president will face, she could be asked for more detail about how she’ll move towards her goal of universal health care within those constraints.