Is Hillary Clinton ready to rumble against Donald Trump? The nation and the world had better hope so.

The question is premature but not unreasonably so. Perhaps Bernie Sanders will stun Clinton in the South Carolina Democratic primary this weekend and then pick off a couple of delegate-rich Super Tuesday states. Maybe Trump’s main challengers, Marco Rubio and Ted Cruz, will start training heavy fire on the guy who’s running away with the Republican nomination.

Such things are possible but do not seem very likely. The Democratic Party’s process of selecting convention delegates is less democratic than the GOP’s; elected officials who serve as “superdelegates” — and who constitute the party establishment — give Clinton a substantial built-in advantage. Sanders’ big victory in New Hampshire, sandwiched between defeats in Iowa and Nevada, hasn’t been enough to start any kind of Obama-style stampede.

If Clinton does as well as pollsters expect in the next few primaries, the Democratic race could effectively be over by mid-March. Her challenge then would be to figure out why turnout in her party’s primaries has been relatively anemic — and fix the problem.

Scaring Democrats and independents to the polls should be easy if Republicans continue on their present course, which is toward some unexplored realm that ancient mapmakers would have labeled “Here Be Monsters.”

Trump’s win in the Nevada caucuses was dominating: He finished with 46 percent, tallying more votes than Rubio and Cruz combined. Rubio and his supporters were left trying to spin a second-place finish, with just 24 percent, into some kind of moral victory. His argument that more than half of GOP voters favored someone other than Trump does not even rise to the level of sophistry, given that more than three-quarters of voters favored someone other than Rubio.

As for Cruz, there wasn’t much he could say at all, except perhaps a quiet prayer that what happened in Vegas would stay in Vegas. Entrance polling showed that Trump beat Cruz among evangelical Christian voters and self-identified conservatives. If Cruz cannot win these segments of the base, what exactly is the point of his campaign?

Perhaps the most ominous sign for those who oppose Trump is that Rubio and Cruz are spending most of their time and money attacking each other rather than aiming at the front-runner.

Rubio believes that if he can make the race a one-on-one contest against Trump, he can win. Cruz has the same strategy. But this logic is flawed. Polls show that Trump is the second choice of substantial numbers of Cruz and Rubio voters. If one of them drops out, the other will get a boost — but so will Trump.

Cruz might win his home state of Texas on Tuesday. Rubio and John Kasich might win their home states — Florida and Ohio, respectively — two weeks later. But Trump seems poised to roll up delegates almost everywhere else and amass what could be an insurmountable lead.

The Republican Party doesn’t have superdelegates; officials play no special role. It is pointless to call for some kind of Trump-blocking backroom deal that nobody has the power to make. And deus ex machina is a plot device in bad novels, not a viable strategy. If Republican primary voters want Trump, they will have him.

So a Clinton-Trump matchup is not only thinkable at this point. It looks — and I can’t believe I’m writing this — almost probable. See? I’m guilty of what I warn against. I wrote “almost” because it is so hard to view this campaign as it is, rather than as I might think it should be.

Clinton would be seen, at least initially, as the prohibitive favorite. But she had better not bring a knife to a gunfight. The biggest challenge for her campaign, which is nothing if not professional and by-the-book, would be to recognize what Rubio, Cruz, Jeb Bush, Chris Christie and the rest of the Republicans failed to see: To beat Trump you have to go after him just as viciously — and cleverly — as he goes after you.

Refusing to descend to his level is a grave mistake. You have to get down and dirty, get under his skin, call him names. You have to worry less about running a campaign the nation can be proud of and more about running a campaign that wins, even if it wins ugly.

Desperate times require desperate measures.