Trump’s surge: GOP’s test

Republican presidential candidate Donald Trump speaks during a South Carolina Republican primary night event in Spartanburg, S.C., Saturday, Feb. 20, 2016. Trump claimed a big victory in South Carolina's Republican primary Saturday, deepening his hold on the party's presidential field as the contest moved into the South. (AP Photo/Paul Sancya)

Donald Trump’s decisive victory in Saturday’s South Carolina Republican presidential primary solidified his front-runner status. It also clarified a major challenge facing the party.

Though many of the tough-talking New York billionaire’s simplistic — and in some cases outlandish — policy proposals are hard to take seriously, he now has a serious shot at winning the GOP nomination.

Mr. Trump’s brash, entertaining flair has transformed the Republican race into a spectacle resembling the reality-TV genre in which he has thrived.

But Americans shouldn’t choose presidents based on who can deliver the most outrageous zinger — or on who can offer the most pandering, hot-button pitch.

Still, Mr. Trump has now won the first two primaries (New Hampshire and South Carolina) by impressive margins after finishing second to Texas Sen. Ted Cruz in the Iowa caucuses.

However, each of those primary victories came with roughly a third of the vote. Do the math: Two-thirds of the voters in those primaries did not choose Mr. Trump. And the once-huge GOP field, which had already dropped to six candidates for our primary, is now down to five due to former Florida Gov. Bush’s exit Saturday night after another dismal finish.

Could Mr. Trump win a head-to-head race if the field drops to just two?

So while it’s understandable that Mr. Trump urged supporters, “Let’s put this thing away,” during Saturday night’s victory speech, there’s still a long way to go.

Florida Sen. Marco Rubio, who won Charleston and Richland counties, apparently edged Sen. Cruz for second. As of now, those two look like the strongest alternatives to Mr. Trump, who won every other county.

But Ohio Gov. John Kasich is still in the race. So is Dr. Ben Carson, assuming he doesn’t also drop out after coming in last on Saturday. And Mr. Trump’s remaining opponents should keep pointing out that his late conversion to conservative ideology is a shift of political convenience.

Meanwhile, they should avoid trading low-brow insults with a master of that craft. Mr. Trump has repeatedly called some GOP candidates — and others — “losers.” He even recently called Mr. Bush “gutless,” Sen. Cruz “a very nasty guy,” and both of them “liars.”

Serious presidential candidates shouldn’t stoop to such juvenile ridicule.

Yet Mr. Trump’s rude — and often downright crude — rhetoric shouldn’t be GOP voters’ biggest objection as he carries his campaign to other states.

His far-fetched policy ideas should.

For instance, he has repeatedly said that he would assure border security and “make Mexico pay for the wall.”

He has pledged to impose massive tariffs on China — a hyper-protectionist step that violates fundamental conservative free-trade economics.

During the Feb. 13 debate in Greenville, he again ignored fiscal reality with the tired dodge that onrushing shortfalls in Social Security revenue could be overcome by eliminating “waste and fraud.” But even the most optimistic projections of Social Security — and Medicare — savings via that route are dwarfed by the heavy, demographically driven burden of Baby Boomer retirements.

Yes, Mr. Trump has tapped into deep frustrations felt by many voters — and not just Republicans.

His GOP rivals must do more than criticize Mr. Trump’s proposals. They must counter those with winning ideas of their own. They should focus on their own records — and on how they would advance the sound conservative principles of free enterprise, fiscal responsibility and a strong national defense.

Otherwise, Mr. Trump’s populist climb to political prominence via superficial showmanship will only roll on.

And that would be a shame for the GOP — and for the nation.