The chaotic frenzy of the Democrats’ South Carolina debate dramatized a generational crisis and a divisive conflict over how damaging the word “socialist” will be in a general election.

There was also this: No candidate other than Sen. Bernie Sanders (I-Vt.) has assembled a coherent and sustainable coalition.

These problems are related because whether Sanders can defeat President Trump — the preoccupation of a large majority of Democratic voters — depends on whether he can rally a large new pool of younger voters to the polls in November.

The evidence so far is not encouraging. Yes, Sanders is the overwhelming favorite among the young, but a huge wave of new voters under 35 has yet to materialize in the first contests.

Seven of the 2020 Democratic presidential candidates shared the stage in Charleston, S.C., on Feb. 25 in the last debate ahead of the South Carolina primary. (The Washington Post)

In the meantime, Democrats who represent swing districts that gave their party control of the House of Representatives fear that Sanders would drive away the more moderate and suburban voters who helped them engineer often-narrow 2018 victories.

For now, Sanders is in a commanding position because, more than anyone else in his party, he has defined its debates since 2016 by shifting the entire political conversation in a more progressive direction. The evidence: Every one of his more moderate primary foes has put forward ideas well to the left of those favored by an earlier generation of centrist Democrats.

As I argue in my book “Code Red,” it was Sanders who spoke for the frustration among progressives, especially younger ones, with a political debate constricted since the Reagan era by right-wing assumptions. After fending off a fall offensive by Sen. Elizabeth Warren (D-Mass.), Sanders stands alone as this constituency’s champion.

And it may come as a surprise, but Sanders’s embrace of “democratic socialism” is actually helping him solidify this bloc in the primaries.

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There are good reasons why young Americans have a far more favorable view of socialism and a more skeptical view of capitalism than their elders. Those under 35 came of age in the wake of the economic system’s near-implosion in the Great Recession, and capitalism simply doesn’t look as good to them in 2020 as it did to the younger generation of, say, 1998.

And polling makes clear that the young are far more likely to associate socialism with Denmark (a happy and prosperous nation that played a supporting role in Tuesday’s debate) than with the long-dead Soviet Union.

But absent the voter surge Sanders is promising, older Americans will vote in a larger proportion in November than the young. And it is among older voters where deep skepticism about socialism rules.

In January, Gallup asked: “If your party nominated a generally well-qualified person for president who happened to be a socialist, would you vote for that person?”

Among adults under 35 years old, 63 percent said yes. But only 42 percent of those aged 35-54 answered affirmatively, and just 35 percent of those over 55 said yes. Even among Democrats, 21 percent said they would not vote for a socialist; for independents, that figure was 51 percent.

The S-word would thus be a heavy burden to carry into a tightly fought campaign, as a timely study by political scientists David Broockman and Joshua Kalla published Tuesday in Vox suggested.

In analyzing an early-2020 40,000-person survey, they found that “nominating Sanders would drive many Americans who would otherwise vote for a moderate Democrat to vote for Trump.”

To offset these losses, Sanders “would need to boost turnout of young left-leaning voters enormously,” Broockman and Kalla wrote. They conclude: “There are good reasons to doubt that Sanders’s nomination would produce a youth turnout surge this large.”

Even Democrats who respect Sanders worry about exactly this. That’s why the candidates who oppose him shouted not just at Sanders but also over and at each other on Tuesday. As time runs short before the Super Tuesday primaries, each is vying to be the non-Sanders alternative who can save the party (and its House majority).

Former vice president Joe Biden may yet become that candidate, especially if his solid debate performance helps him win Saturday’s South Carolina primary.

But it’s late, and the yearning for someone other than Biden continues to scatter the non-Sanders vote, with former South Bend, Ind., mayor Pete Buttigieg being the primary beneficiary of Biden anxiety.

Sanders has an argument, a base and a lot of energy behind him. His foes have a strong case that he can’t deliver on his promise to create a new electorate. But to get past him, one of them will need more than shouted warnings of impending catastrophe.

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