Cue the class warriors.

Bill de Blasio’s startling emergence as the dominant presence in New York City’s Democratic mayoral primary — or, at least, at the top of one conversation-setting public poll — should surprise no one.

Class warfare works everywhere these days — witness President Obama’s smooth-as-silk re-election last year — and who could doubt that it wouldn’t pay dividends in Gotham?

Oops. Shouldn’t say “pay dividends.” That’s what they do down on Wall Street. Evil. Evil.

De Blasio first popped out of the pack a week ago — and by this Wednesday he was so far ahead in the Quinnipiac University poll it seems possible he could avoid a runoff election after the Sept. 10 primary.

He has done this by pushing the basic hot buttons — class and race — like he was playing a video game.

Subtly, of course, but deliberately and to obvious good effect.

On class, his message is clear: I’ll squeeze “the rich” like an orange — and you’ll get the juice.

On race, he promises a radical reorientation of the police department — a grossly irresponsible approach, but one designed to capitalize on historic resentments.

Yes, all of the major Democratic candidates are in full pander regarding the NYPD. Without rehashing old arguments, let’s note new policies that discourage aggressive anti-street-crime policing will be paid for in blood down the road, and the blame will be on all of them.

De Blasio’s economic rabble-rousing, camouflaged as an education initiative, deserves a closer look than it’s gotten — both as a policy proposal and as a political ploy.

Here’s the policy: De Blasio intends to hike taxes on millionaires — he says the city has 400,000 of them — to raise $530 million annually for vaporously defined pre-kindergarten and after-school programs. Easier said than done, but a clear statement of purpose.

Here’s the politics: Everybody knows that it’s impossible to spend too much money on “the children,” and if a little more coin can be scraped up by gouging the greedy bastards on Wall Street again — hey, let’s go for it.

This message, delivered with a smile, quite obviously is resonating with the electorate’s more-free-stuff component, which comprises a disproportionate share of the Democratic primary vote.

But here’s something the free-stuffers don’t want to hear: If de Blasio’s education initiative is worth doing — that is, if it’s to be something more than a tax-funded baby-sitting service mostly of benefit to the United Federation of Teachers — there’s no reason to raise taxes on anybody to pay for it.

Certainly $530 million is a lot of money. But it amounts to less than eight-tenths of 1 percent of the city budget — and a mayor who isn’t clever enough to suss that out of current revenues probably isn’t clever enough to be mayor in the first place.

Assuming the program is the point. Which, again, is not.

The politics of envy and resentment — de Blasio’s “two New Yorks” theme — is the point.

Yes, there is “income inequality” in the five boroughs. There always has been — though the post-World War II hollowing out of America’s industrial employment base has certainly made matters worse.

Many of the city’s economic wounds are self-inflicted — its ruinous tax load and its corrosive regulations have inflicted grievous and probably irreversible damage, and it shows. Today, New York City’s economy seems to be bubbling, and to a certain extent it is. But tenuously.

The current good times are driven by two great engines: Wall Street and tourism. Both have prospered from 20 years of adult leadership in City Hall, and both of them have been targeted by de Blasio’s soft-sell populist campaign.

Nobody on Wall Street is missing the message in his “tax the rich” rhetoric. It may start with the pre-school levy, but — just as Gov. Cuomo couldn’t resist sipping from that well two years ago — a Mayor de Blasio would be back for a second slug. If not a third.

So, in an age of instant digital communication, how long before the sheep refuse to be shorn — and simply split?

And, as the Democrats’ anti-cop campaign erodes public safety, how long before the tourist trade notices and begins once again to fade?

There likely would be no catastrophic decompressions. But even gradual economic decline isn’t the only danger in de Blasio’s approach.

Moreover, one poll, however tectonic, doesn’t necessarily mean much in traditionally volatile Democratic primaries. Maybe not even two.

But the trend seems clear. And it leads down a dreary, dangerous path. Best to steer clear.