Elizabeth Warren wants to abolish private health insurance. Uh oh.

Is it possible to pluck one newsworthy moment from last night’s cacophonous 10-contestant Democratic quiz show? You bet. Here we go:

Moderator Lester Holt asked, “Who here would abolish their private health insurance in favor of a government-run plan? Just a show of hands.”

Elizabeth Warren raised hers.

To which I say: Uh oh. Warren is a solidly top-tier candidate, with a decent shot at winning the nomination, but, politically speaking, I seriously question whether someone who wants to abolish the private health care of 180 million Americans can actually win a general election. For reasons I’ll soon explain.

Blessedly, however, her bold announcement did bring some momentary clarity to the predictable Democratic clustermuck. Half the people on last night’s stage (and half the people slated for tonight’s 10-contestant stage) will soon be answers to trivia questions. Tulsi Gabbard and Tim Ryan, sparring at length? Please. If I want to watch cellar dwellers, I’ll find a Royals-Orioles ballgame. Ryan, Jay Inslee, and John Delaney? I couldn’t tell those white guys apart; they all looked like high school wrestling coaches. And Beto O’Rourke? He may look good jumping on tables, but he was thrashed last night, on the issue of immigration, by the more experienced Texan on stage, Julian Castro.

But anyway, Elizabeth Warren was the sole candidate on stage who’s polling in double digits, crowding Bernie Sanders for second place behind Joe Biden. Her words counted the most. She was also the sole person on stage (except for one-percent candidate Bill de Blasio) who called for the abolition of private health insurance — a stance she hadn’t articulated on the campaign trail. Here’s what she said last night:

“I’m with Bernie on ‘Medicare for all.’ And let me tell you why. I spent a big chunk of my life studying why families go broke. And one of the number one reasons is the cost of health care, medical bills. And that’s not just for people who don’t have insurance. It’s for people who have insurance.

“Look at the business model of an insurance company. It’s to bring in as many dollars as they can in premiums and to pay out as few dollars as possible for your health care. That leaves families with rising premiums, rising co-pays, and fighting with insurance companies to try to get the health care that their doctors say that they and their children need. ‘Medicare for all’ solves that problem.

“And I understand. There are a lot of politicians who say, ‘oh, it’s just not possible, we just can’t do it, have a lot of political reasons for this.’ What they’re really telling you is they just won’t fight for it. Well, health care is a basic human right, and I will fight for basic human rights.”

Her stance may enhance her nomination prospects, within a party that has moved leftward since 2016. Most grassroots Democrats likely won’t fault her critique of the private insurance companies, and lots of centrist swing voters with private coverage have their own complaints about the status quo system. But in politics, you don’t necessarily win awards for great intentions, or for articulating the most rational arguments. Warren conceded that there are “political reasons” for not supporting government health care, but she didn’t say what they are.

So I will. It’s quite simple, actually:

A landslide majority of Americans like their private health coverage, and they don’t want it taken away. Indeed, voters in general don’t like it when politicians try to take something away.

Granted, most Americans reportedly support the nebulous concept of “Medicare for all,” but as soon as they’re confronted with caveats, it’s a different story. According to the nonpartisan Kaiser Tracking Poll, “Medicare for all” gets a thumbs-up rating, 56 to 42 percent. But when Americans are told that the program could eliminate private health insurance — as Bernie Sanders’ agenda envisions, phasing out private coverage within four years — most people run for the hills. The numbers are suddenly reversed: 37 percent yes, 58 percent no.

Imagine what Trump and the Republicans would do with that, if Warren or Sanders were nominated. And on this issue, they wouldn’t even need to lie. Warren is confident about her powers of persuasion (and, in many cases, rightly so), but it’s hard to foresee her winning the argument for government health care. Fairly or not, “socialism” is a word that’s easy to demagogue, and Americans (especially those 45 and older, the most reliable voters) simply don’t like the word. They may be blind to the socialistic initiatives that they’ve long enjoyed (from Social Security to the interstate highway system), but that’s just political reality. Which is why candidate Kamala Harris, who is slated for tonight’s debate, has walked back her early support for abolishing private health insurance.

Amy Klobuchar, who has gotten little traction in the race thus far, said on stage last night: “I am just simply concerned about kicking half of America off of their health insurance in four years.” For the Trump campaign and the GOP, that’s the perfect video clip — an acknowledgment, from a Democrat, that Warren would imperil “half of America.” And Joe Biden’s campaign is drawing a sharp contrast with Warren, endorsing the more incremental approach to health reform; in a statement last night, it said: “The Biden administration will give every American the right to choose a public option like Medicare.” (Clever use of “right to choose.”)

So we did get some clarity last night, at least on the top-tier issue of health care: government coverage versus incremental reform. Should the Democrats go boldly leftward, or practice prudent moderation?

Elizabeth Warren wowed the liberal base, but she may have teed up the GOP’s top attack ad and rendered herself less electable.