The one thing we know about health care in the 2020 Democratic presidential primary race is that it's a top issue for voters.

The latest Tracking Poll from the Kaiser Family Foundation in late November found 24% of Democrats and Democratic-leaning independents said they want to hear the candidates discuss health care. That's twice the total for the next top issue, climate change, and four times the total for immigration, the No. 3 issue.

The big question, though, is whether that interest will reward a candidate who backs a sweeping "Medicare for All"-type plan, or, instead, a more modest plan like a public option, in which a person can voluntarily join a government health insurance plan if they choose to.

Polling doesn't make that clear. On the one hand, Democrats and Democratic-leaning respondents in the KFF poll say when it comes to health care, the candidate they trust most is Sen. Bernie Sanders of Vermont (who has been pushing a Medicare for All plan since at least 1993).

Yet those same people say they prefer a public option (of the sort supported by former Vice President Joe Biden) to Sanders' Medicare for All plan.

That voter preference for the public option strategy was borne out in a separate Quinnipiac poll released last week, in which 36% of respondents say Medicare for All is a good idea while 52% say it is a bad idea. An NBC/Wall Street Journal poll from September found similar results: 67% of respondents said they would support allowing people younger than 65 to "buy their health coverage through the Medicare program," while only 41% favored "adopting Medicare for All, a single-payer health care system in which private health insurance would be eliminated."

So, what the candidates now face is a question of strategy and tactics.

Sanders is all in on Medicare for All. "I wrote the damn bill," he keeps reminding reporters. Biden and the rising-in-the-polls Pete Buttigieg, the mayor of South Bend, Ind., are firmly in favor of a more moderate approach.

"We take a version of Medicare. We let you access it if you want to. And if you prefer to stay on your private plan, you can do that, too," Buttigieg said at the Democrats' October debate. "That is what most Americans want."

Sen. Elizabeth Warren of Massachusetts looks like she is trying to have it both ways. She has unveiled a far more detailed version of Medicare for All than Sanders or other backers of the concept in Congress. And her campaign has unveiled a "first-term" health plan that could be implemented quickly, moving to a broader Medicare for All system later in her first term. (Even Warren's transitional plan is more expansive than either Biden's or Buttigieg's plans.)

Who's right? There's no good way to tell until voters actually cast their ballots. But it might surprise people that the last time a health overhaul was a major issue in the Democratic presidential primary race ― in 2008 — it wasn't the candidate with the most sweeping plan who emerged as the winner.

Then-Sen. Hillary Clinton had a more sweeping plan for health care than her Senate colleague Barack Obama. Clinton called for a cap on out-of-pocket medical expenses and an "individual mandate" — a requirement (repealed by Republicans in 2017) that people either prove they have health coverage or pay a fine.

Obama resisted many of those specifics, particularly the mandate. "In order for you to force people to get health insurance, you've got to have a very harsh, stiff penalty," he said at a debate in February 2008. Eventually he called for a mandate that all children have coverage. Obama did not fully embrace the mandate that would become part of the Affordable Care Act until mid-2009, during the congressional debate.

But proponents of Medicare for All argue that Democratic primary voters have moved significantly to the left since 2008.

That is clearly the case. Still, if Democrats are to keep control of the House of Representatives, they will need to keep the loyalty of those independent voters in districts that are far more moderate than those represented by left-leaning lawmakers such as Alexandria Ocasio-Cortez, D-N.Y., and Ilhan Omar, D-Minn., who are pressing for major changes, including the passage of a Medicare for All plan.

The key to becoming the Democratic presidential nominee, of course, is threading the political needle in a way that keeps the enthusiasm of the Democrats' Medicare for All base, while not scaring away voters in swing areas who fear such major changes. So far, not one of the presidential candidates has found that perfect spot. The one who does could well be the next president.

Kaiser Health News is a nonprofit, editorially independent program of the Kaiser Family Foundation. Neither KHN nor the Kaiser Family Foundation is affiliated with Kaiser Permanente.

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