Clinton is arguing logic versus Sanders’ fantasies. She must make her case in South Carolina.

In the early contests for the Democratic presidential nomination, self-described democratic socialist Bernie Sanders has given former U.S. Senator and Secretary of State Hillary Clinton more than a run for her money. After achieving a virtual tie in Iowa and trouncing her in New Hampshire, Sanders on Saturday dogged Clinton in Nevada — a state in which she had hoped an ethnically diverse population would work to her advantage.

He now takes the fight to Clinton next Saturday in South Carolina, where he stands well behind her in state polls. Still, the latest national surveys suggest that Sanders has gained extraordinary momentum across the country by railing about the success of the wealthy and the plight of the working and middle classes.

Sanders’ economic message is resonating both because it the right message for the moment and his passion is real. Who cares that he is ill-prepared for the White House? In the end, voters must.

Clinton faces a critical challenge in erecting a fire wall in South Carolina, with the support of the state’s once-loyal African-Americans. Simply put, she will have to stop being her own worst enemy.

While Sanders speaks authentically — and repetitively to a fault — Clinton often appears to calculate.

While Sanders is people-powered, Clinton has collected large checks, and speaking fees, from big banks — poison in a populist political climate.

While Sanders, lacking a record to speak of, is scandal-free, Clinton is dogged by sending and receiving State Department email on an unsecured home-brew server.

All of that said, Clinton would be a far stronger general election candidate than Sanders, and she far outpaces him in the ability to make strides once in office.

For her, politics is the art of the possible; for him, it’s the art of yelling that fantasies will come true because they must come true.

He imagines free public college for all — the wealthy, the middle class and the poor alike — plus single-payer health care. His policies would ex- pand the federal government by more than 40%, devour taxes and, inevitably, weigh down the economy.

In a blistering open letter, four former chairs of the Council of Economic Advisers — liberals all — exposed the impossibility of Sanders’ commitments.

“Making such promises runs against our party’s best traditions of evidence-based policy-making and undermines our reputation as the party of responsible arithmetic,” they wrote.

Indeed, even Gerald Friedman, a liberal University of Massachusetts economist who outlandishly asserted that Sanders would grow the economy by leaps and bounds, has said that he’ll vote for Clinton.

Meantime, Sanders knows next to nothing about the world; he is plainly uncomfortable when asked to explain how he would answer threats to national security, and has yet to name foreign policy advisers.

Clinton, a strong center-left legislator and tough-minded secretary of state, has put forward pragmatic ideas that stand a chance in a divided Congress.

She would aim to raise wages through tax credits for the middle class and small businesses, as well as through major investments in infrastructure, basic science and energy.

She would work to fix Obamacare’s weaknesses without throwing the nation back into an allconsuming debate over transforming its health care system.

She would bring down the cost of college — not via haphazard Sandersian spending, but by facilitating the refinancing of loans and help middleand lower-income strivers meet expenses.

She has been a strong voice for gun safety regulations; Sanders has not.

She would face America’s friends and enemies alike with unmatched experience.

Unlike the Sanders sloganeering, the Clinton agenda doesn’t fit on a postage stamp. She is arguing logic against passion. It’s a tough sell. Now is the time, and South Carolina is the place, for her to make it.