Sen. Kamala Harris committed a most unusual gaffe at her CNN town hall the other night — not by misspeaking about one of her central policy proposals, but by describing it accurately.

Asked on Monday night if the “Medicare-for-all” plan that she’s co-sponsoring with Sen. Bernie Sanders eliminates private health insurance, she said that it most certainly does. Citing insurance company paperwork and delays, she waved her hand: “Let’s eliminate all of that. Let’s move on.”

She met with approbation from the friendly audience in Des Moines, Iowa, but the reaction elsewhere was swift and negative.

“As the furor grew,” CNN reported the next day, “a Harris adviser on Tuesday signaled that the candidate would also be open to the more moderate health reform plans, which would preserve the industry, being floated by other congressional Democrats.”

This was a leading Democrat wobbling on one of her top priorities 48 hours after the kickoff of her presidential campaign, which has been praised for its early acumen. It is sure to be the first of many unpleasant encounters between the new Democratic agenda and political reality.

Democrats are now moving from the hothouse phase of jockeying for the nomination, when all they had to do was get on board the party’s orthodoxy as defined by Bernie Sanders, to defending these ideas in the context of possibly signing them into law as president of the United States.

The Harris flap shows that insufficient thought has been given to how these proposals will strike people not already favorably disposed to the new socialism. It’s one thing for Sanders to favor eliminating private health insurance; no one has ever believed that he is likely to become president. It’s another for Harris, deemed a possible front-runner, to say it.

Her position is jaw-droppingly radical. It flips the script of the (dishonest) Barack Obama pledge so essential to passing Obamacare: “If you like your health care plan, you’ll be able to keep your health care plan, period. No one will take it away, no matter what.”

That was a very 2009 sentiment. Ten years later, Harris indeed wants to take away your health plan, not in a stealthy operation, not as an unfortunate byproduct of the rest of her plan, but as a defining plank of her agenda.

This is a far more disruptive idea than Sen. Elizabeth Warren’s wealth tax. The affected population isn’t a limited group of highly affluent people. It is half the population, roughly 180 million people who aren’t eager for the government to swoop in and nullify their current health care arrangements.

They may not like the current system, but they like their own health care — about three-quarters tell Gallup that their own health care is excellent or good. This is why the relatively minor interruption of private plans as part of the rollout of Obamacare was so radioactive.

How is a President Harris going to overcome this kind of resistance absent Depression-era Democratic supermajorities in Congress? Not to mention pay for a program that might well cost $30 trillion over 10 years and beat back fierce opposition from key players in the health-care industry?

She obviously won’t. “Medicare-for-all” is a wish and a talking point rather than a realistic policy. When her aides say she is willing to accept another “path” to “Medicare-for-all,” what they mean is that Harris is willing to accept something short of true “Medicare-for-all.”

There is always something to be said for shifting the Overton window on policy. But it’s better if that is done by think tanks and gadflies rather than plausible presidential candidates who aren’t even trying to hold down the left flank of the party.

If it’s uncomfortable for Kamala Harris to defend eliminating private health insurance now, imagine what it will be like when the entire apparatus of the Republican Party — including the president’s Twitter feed — is aimed at her in a general election.

Rich Lowry is a syndicated columnist. He can be reached via e-mail at: comments.lowry@nationalreview.com.

Rich Lowry