A member of the audience holds up a placard as Sen. Bernie Sanders (I-Vt.) discusses Medicare-for-all legislation on Capitol Hill in Washington. (Jim Watson/AFP/Getty Images)
Contributing columnist

In 2018, Democrats won the midterm elections on the issue of health care, specifically protecting the Affordable Care Act and its guarantee of coverage for pre existing conditions. It was a hard-earned victory: Passing the ACA was a major reason Democrats lost the House and seats in the Senate in 2010 , and polls showed the ACA was not a winner for Democrats in 2012, 2014 or 2016. Now, the question is: Having won the upper hand on health care, will Democrats give it back in 2020?

What might squander that advantage? A primary battle among Democrats who all favor universal coverage but have differences about how to get there. Candidates seeking advantage in that contest by questioning the purity of one another’s views on health care, or conversely, trying to scare voters with nightmare scenarios about those with more liberal views. And most important, a focus on internecine differences instead of on the sharp contrast between the core Democratic position and the Republican stand on the future of health coverage in our country.

The first warning sign was the recent false debate over whether any potential Democratic candidates favor abolishing private health insurance as part of their support for Medicare-for-all. None do. The Medicare for All Act explicitly says: “Nothing in this Act shall be construed as prohibiting the sale of health insurance coverage for any additional benefits . . . including additional benefits that an employer may provide to employees . . . or to former employees.” In fact, many Americans already on Medicare also have some form of private insurance, whether it is private-company retiree health benefits or a “Medigap” plan to cover services that Medicare doesn’t.

But the statements from Sen. Kamala D. Harris (D-Calif.) at a CNN town hall underscoring the obvious pain points many encounter when using private insurance were portrayed as a desire to ban all private coverage. And Sen. Cory Booker’s (D-N.J.) subsequent acknowledgment that private insurance would remain in a Medicare-for-all world was painted as a rebuke of Harris . Neither is correct.

Nor is expanding Medicare some radical departure in our system. One in three Americans already gets coverage from Medicare or Medicaid — far more than are covered by any private insurer. Expanding that coverage isn’t “un-American ” (unless one-third of the country is “un-American”); Medicare expansion should not scare anyone or suggest an end to private coverage as part of our system.

Yes, there are differences among the Democrats running for president. Some favor all Americans getting their basic coverage from a restructured Medicare. Others may back a plan that would allow all Americans to choose between Medicare or continuing to get their basic insurance from private carriers. Still others back a more limited growth in Medicare, expanding its reach to those age 55 or older.

The differences are important, but two critical points are even more significant. First, overwrought hair-splitting among the primary contenders’ positions proves little about what any would actually do as president. In 2008, Hillary Clinton and Barack Obama waged a fierce battle over whether an “individual mandate” — requiring each person to buy health-care coverage — should be part of health-care reform. Obama opposed the mandate during the campaign and then put one in his health-care plan once in office.

Likewise, most of 2020’s Democratic contenders — no matter what their apparent differences on the campaign trail — are likely to work toward essentially the same policies once in office: strengthening the Affordable Care Act, expanding Medicaid and creating a path to universal coverage under Medicare. The devil may be in the details, but Satan will be wrestled to the ground in the Oval Office, not the Iowa caucuses.

Second, Democrats cannot let relatively minor differences between them over how to achieve universal coverage overshadow the real divide in U.S. politics: the gaping hole between Democratic plans to expand health-care coverage and the relentless Republican pursuit of the wish list of the health insurance industry.

Republicans in Congress spent years doing everything they could to repeal the ACA. If they had gotten their way, millions would have lost their coverage, and tens of millions would have had no protection from insurance company abuses, such as denying coverage due to preexisting conditions or cutting off coverage after patients hit a “lifetime cap.” Once in power, and after they were unable to repeal the law, President Trump pushed forward an agenda to shred state regulation of insurance companies and allow a single state regulator captured by insurance interests to greenlight “sham insurance” plans for sale coast to coast. And on Trump’s watch, the percentage of Americans lacking coverage has climbed , and the number of families getting covered under the ACA has fallen .

Democrats should not let 2020 be about their differences on health care. They need to get sharper at turning the argument around. The question in 2020 should not be why most Democrats want to give more Americans the opportunity to have Medicare coverage instead of private health insurance; the question should be why Republicans are so determined to keep Americans trapped in the world’s most expensive, bureaucratic health coverage system, which serves so many so poorly, and so many others not at all.