A prominent liberal think tank just put out an ambitious new health care proposal .

That doesnt sound like news, until you consider which think tank it is and exactly what its proposing.

The think tank is the Center for American Progress , which is based in Washington and has close ties to the Democratic Party establishment. The proposal, which its authors call Medicare Extra for All , would create a new public program, based on Medicare, that would be open to anybody.

The proposal, which Ricardo Alonso-Zaldivar of The Associated Press first reported Wednesday evening, also calls for automatically enrolling the uninsured, among others, in this new program in the hopes of finally achieving universal coverage.

Some will call this plan a single-payer proposal, because its easy to imagine, someday, everybody being part of this new version of Medicare. Some will say its not a single-payer proposal, because it envisions a permanent, potentially large role for private insurance as a provider of highly regulated plans that would function more or less the way private plans for seniors on Medicare operate today.

But whatever the proposals label, its plainly a more ambitious and more progressive health plan than the Democratic Partys most influential thinkers have embraced in the past. And thats what makes it noteworthy.

Its a reflection of how far the partys internal conversation has shifted in the direction of government-run insurance even since the 2016 presidential campaign, when Sen. Bernie Sanders (I-Vt.) made a pure single-payer system the cornerstone of his Democratic primary run. Its also a leading indicator of how Democrats plan to approach health care as they start thinking about the 2020 presidential campaign.