Mike Bloomberg is cool, correct and effective, and all the more worrisome for it.

If November were to come down to a Trump-Bloomberg race — despite the former New York City mayor’s woeful debating skills — Americans would get the choice of swapping one president with an a-constitutional view of the office for another.

The two New York City billionaires are studies in contrast, except no one would think to feature either one of them in an episode of “Schoolhouse Rock.”

Trump views the presidency through the prism of what’s most gratifying to him, especially his insatiable need for attention; Bloomberg would view it through the prism of what’s good for you, as filtered through his supreme confidence that, he, and only he, truly knows what that is.

Trump’s ego feeds off constant praise and airtime; Bloomberg’s feeds off his belief that he’s the smartest guy in the room, in fact, in any room, and that you’d inevitably agree with him if only you were as intelligent, rational and public-spirited as he is.

Trump insults people directly with disparaging nicknames and slighting references to their physical characteristics, energy level and poll numbers; Bloomberg insults them indirectly with his ill-disguised contempt for their supposedly troglodyte views if they happen to disagree with him.

Trump the nationalist wants to control the flow of foreign people and goods into the United States; Bloomberg the do-gooder wants to control your diet and other habits.

Both Trump and Bloomberg have a soft spot for Chinese president-for-life Xi Jinping. For Trump, he is strong; for Bloomberg, he is able to do what he wants with minimal interference from little people and non-experts.

The signature Michael Bloomberg initiative is the ban — of smoking, of large sodas, of guns. He is most comfortable when he is prohibiting things that people should know better than to consume or own.

The spirit of these initiatives was un-democratic and in some cases, the method was, too. Bloomberg bypassed the City Council when attempting to impose his soda ban, instead getting the Board of Health to issue a diktat against 16-ounce sodas sold at the wrong establishments.

Surely, to the extent it’s made any impression on him whatsoever, Bloomberg considers the US Constitution an anachronism that poses obstacles to the initiatives of right-thinking people. Why should an 18th-century conception of rights get in the way of 21st-century government, especially when health and safety are at stake?

Bloomberg’s reaction after the Boston Marathon bombing was characteristic: “We live in a complex world,” he said, “where you’re going to have to have a level of security greater than you did back in the olden days, if you will. And our laws and our interpretation of the Constitution, I think, have to change.”

What he so dismissively calls “the olden days” was the time of the American Founding, and the idea that the Founders didn’t understand complexity, or have any sense of trade-offs, is ahistorical nonsense.

It is important that Trump, whatever his personal and institutional failings, is backstopped by a conservative legal movement that has worked with him to pump originalist judges through the Senate. These judges will remain a bulwark of conservative constitutionalism long after Trump has departed the scene.

Bloomberg’s technocratic instincts, in contrast, run with the grain of contemporary progressivism. There will be no checks on his natural tendency toward unilateral rule through the administrative state. In fact, support for this mode of government is shared by his fiercest Democratic critics like Elizabeth Warren, who may scorn Bloomberg but has openly embraced government by presidential decree.

Democrats may yet come to believe, should their nomination battle break the right way, that only Mike Bloomberg can save the country — but what he emphatically won’t be saving is a view of the government as circumscribed by an old, yet sacrosanct Constitution.

Twitter: @RichLowry