Donald Trump is running riot in the GOP china shop and gleefully tearing the place up.

Consider the strength of Trump’s position: If he wins South Carolina by a big margin, he goes into Nevada with momentum, and the latest poll there has him leading by 26 points. If he enters Super Tuesday a week later having won three out of the past three states — and with Ted Cruz diminished by a South Carolina loss and Marco Rubio having won nowhere — he could easily win, say, 10 contests that day.

It might still be possible to beat Trump at that point if the field is narrowed (states don’t become winner-take-all until March 15), but doing so would involve wrestling to the ground a candidate who will have cut a formidable swath through the first month of the nomination battle.

Even now, it’s hard to imagine a happy outcome for the party from the three likeliest scenarios:

— If Trump wins the nomination outright, many Republican voters may stay home, and senators and members of the House up for re-election will scurry for cover.

It is certainly possible that Trump will prove a better general-election candidate than expected, just as he has proved a much more potent candidate in the primaries than nearly anyone thought. But it also is likely that the general public will be less enamored or forgiving of those qualities in Trump that have charmed or at least not bothered a plurality of the Republican electorate — the lack of political experience, the foul mouth, the constant psychodrama, the spotty business record.

— If Trump is dragged to an open convention and leads in delegates, but falls short of a majority and is denied the nomination, there will be a bloodbath. Trump will make Andrew Jackson’s angry cry of a “corrupt bargain” after Old Hickory lost the presidency in the House of Representatives in 1824 — despite leading in popular and electoral votes — look like a measured, coolheaded response. Trump will stomp off, and no doubt take a lot of his supporters with him.

— If Trump is beaten prior to a convention, it will presumably require an all-out war against the mogul. Well-heeled Republican donors will have to pour money into a thermonuclear advertising campaign to destroy his image. The party will have to do everything in its power to bolster a Trump alternative. Such an effort will no doubt strike Trump as “unfair,” and he will do all he can to delegitimize it and find targets to sue over it. Needless to say, none of this would be conducive to keeping Trump voters inside the Republican tent.

Has any political party ever had a candidate who is such a wrecking ball, and who isn’t a fringe candidate, but a dominant one?

The Republican front-runner is threatening to sue one of his challengers. The Republican front-runner thinks the last Republican president was guilty of impeachable offenses and lied the country into war. The Republican front-runner routinely attacks his own party for its perfidy — he claims the Iowa caucuses were stolen from him and the debate audiences are stacked against him — and insults his competitors in the harshest, most personal terms.

We’ve grown used to how Trump has treated Jeb Bush in the debates, but that doesn’t make it any less appalling a breach of basic decency. The faces he makes while Bush talks, the constant interrupting, the petty put-downs — all of this would have been thought unworthy of the lowest political guttersnipe but have become an accepted part of the landscape thanks to Donald J. Trump.

The key to Trump’s strength, which buttresses all his outrageousness, is that his supporters want someone to blow up the system. So there’s almost nothing he can say or do that will discredit him in their eyes, and the least destructive scenario for his defeat — Trump blows himself up — will take some doing on his part.

It’s all very entertaining — but so are demolition derbies.

Rich Lowry can be reached via e-mail: comments.lowry@nationalreview.com.