Donald Trump’s crushing across-the-board victory in New Hampshire had the breadth and depth that one would expect of a future nominee. If the result doesn’t shake the lazy complacency about Trump that has held in Republican circles for months — and was reinforced by his disappointing Iowa finish — nothing will.

The question is no longer whether Trump will fade. It’s whether he can be stopped and who is actually going to do it and on what terms.

Trump has many unusual characteristics for a Republican front-runner. Among the weirdest is that with the exception of the furious last few weeks before Iowa — when the faux Ted Cruz-Donald Trump bromance finally ended — he hasn’t been subjected to sustained attack. Yes, the Lindsey Grahams and Jeb Bushes of the world have been yapping at him, but there hasn’t been a concerted effort to blunt his appeal.

It’s possible that New Hampshire is being over-read. The state can have idiosyncratic tastes. It gave its nod to Pat Buchanan in 1996 and to John McCain in 2000, in a victory over George W. Bush as crushing as Trump’s Tuesday night.

Buchanan was done in by his own limits as a candidate. Trump is a more potent performer, and is running at a moment when the Republican electorate is dry tinder for a cleansing populist fire. McCain, on the other hand, was dismantled piece by piece in South Carolina in a ferocious counterassault by the Bush machine.

Will there be such a campaign against Trump? So far the opposing candidates have been too consumed with (understandable) tactical considerations to turn on him in a serious way.

Marco Rubio was rooting for Trump to win Iowa to damage Cruz, and never got close enough to Trump in New Hampshire to shoot at him. Cruz hit Trump in Iowa and in the immediate aftermath, when Trump accused him of stealing the caucus, but ducked and covered in New Hampshire, where he wanted Trump to win to damage Rubio (it turned out it wasn’t necessary).

Jeb Bush has been the most consistently anti-Trump candidate. He has also, as an earnest representative of a political dynasty, been the perfect foil for him and routinely complains that Trump is divisive, not exactly a cutting critique for Trump-friendly voters.

As for the Republican establishment, it exists, but is a shell compared to the overwrought image of it as an all-powerful force. It is fractured, confused and pusillanimous (Trump would use a more pungent phrase).

It is, in part, frozen by the Bob Dole-Jimmy Carter consensus that Cruz is a dangerous, overly rigid ideologue in the field. In this view, there are few things as distasteful as someone who firmly believes in ideas. So nothing can be done to harm the unapologetic demagogue, lest it indirectly help Cruz.

The logic goes: Wait a while longer. Maybe Trump can kill Cruz in South Carolina. And then Bush, Rubio or possibly John Kasich can sweep in and pick up the pieces.

This was the idea prior to Iowa as well, and if it had worked out — if Cruz hadn’t pulled off an upset victory — Trump would have an even more formidable head of steam right now.

Everyone imagines that he’ll win in a matchup with Trump. Cruz wants a two-way race with Trump. Bush and Rubio want to get in a three-way race with Cruz and Trump. But there’s no guarantee that Trump won’t get stronger.

The “rules” of politics may have been partly suspended as Trump taps into an abiding disgust with politics-as-usual. But some rules still apply: Momentum matters. Victories are validating. If Trump continues to run free, he gets harder to stop, not easier.

At least the interval between New Hampshire and South Carolina should resemble the final push in Iowa, with Cruz engaged in trench warfare with Trump. And so the task of foiling a hostile takeover of the GOP will, once again, fall to the man that the party’s mandarins disdain most.

Rich Lowry is a syndicated columnist. He can be reached via e-mail at: comments.lowry@nationalreview.com.