Sen. Bernie Sanders (I-Vt.) plans to unveil a new version of his Medicare-for-all proposal on Wednesday. But the actual substance of the plan may matter less than what he says about it and the role he envisions that proposal playing in future debates over how to reform the U.S. health care system.

He could try to make it a litmus test, by presenting his proposal as a near-finished piece of legislation and demanding that Democrats pledge fealty to its particulars. Or he could present it more as a concept, something he expects progressives to spend the next few years refining, with a greater emphasis on the goal of truly universal coverage than the specific means for achieving it.

The former approach sounds bolder. The latter could ultimately do more to make health care available and affordable.

Why Berniecare Is Getting Traction After All These Years

Certainly Sanders has earned the right to talk about Medicare-for-all. Hes among a small group of public officials who have been pushing the idea literally for decades, no matter what the political climate. And if he hadnt made the concept such a prominent part of his 2016 presidential campaign, nobody but a handful of relatively low-profile progressives would be talking about it now.

Instead, Democratic senators are lining up to co-sponsor his bill, including four (Cory Booker of New Jersey, Kirsten Gillibrand of New York, Kamala Harris of California and Elizabeth Warren of Massachusetts) who are potential Democratic presidential candidates for 2020. An even more unexpected endorsement of the concept, if not the Sanders proposal specifically, came last week from Max Baucus , the relatively conservative former Democratic senator from Montana who was a key architect of the Affordable Care Act.

The resurgence in interest makes sense. The Affordable Care Act has helped millions to get insurance, improving access to care and offering financial security many lacked before. It also created a political consensus behind the essential principle of universal coverage that everybody should have insurance, regardless of income or medical condition.

But the law has also fallen short of realizing that goal. Millions of Americans still dont have insurance. Millions who do are stuck with high premiums or out-of-pocket expenses. The new system seems to have particular trouble in more rural parts of the country, where sparse populations make it difficult for private insurance markets to thrive. Thats why Republicans have been able to get as far as they have with their repeal effort and why even Democrats are talking about how theyd like to improve the system.