There’s no mystery why Zohran Mamdani wanted to get along with Donald Trump. The president threatened New York City with funding cuts, deployment of federal forces and other unpleasantries if its voters elected the self-described democratic socialist as mayor. But why after calling Mamdani all kinds of names, even warning of his possible arrest, did Trump later smother the mayor-elect with flamboyant affection?

An explanation: The MAGA show is closing — as is Trump’s time in the White House. Trump needs a new forum on which to stage his dramas.

New York may seem a natural place for the man who, before becoming president, styled himself as Mr. New York. Mamdani could ease Trump’s way back in.

Of course, Trump has other places to go after the White House.

Mar-a-Lago would be an obvious choice. Problem is, Palm Beach will be much less lively once Trump can no longer dispense government favors to rich hangers-on.

There’s “Trump Country,” one supposes. The problem there is he’s leaving much of Trump country in shambles.

Besides, wild horses couldn’t drag Trump to the places that most loved him. Not enough models. Not enough monied nightspots.

But Trump will be 82 when he leaves office. He’s no longer the swinging young buck who gamboled his way onto tabloid covers. New Yorkers didn’t particularly hate Trump. They regarded him as an amusing rogue.

Mamdani is also a cagey guy and unlikely to let Trump play him. Trump’s offer to help him “Make New York Great Again” didn’t play so well in Gotham. New York already regards itself as great. It’s much of the MAGA heartland that doesn’t seem to be doing so great.

On the other hand, as long as Trump controls the federal government, he has carrots to dangle. New York Gov. Kathy Hochul has pretty much shot down Mamdani’s plan for free buses.

The state runs the region’s transportation system, and she is not keen to provide the $800 million that would be needed. But didn’t Trump offer to work with the next mayor for the betterment of New York City? Consider that $800 million is nothing in Washington. Trump could do the free buses in return for something personal.

Now, becoming bros with Trump would be problematic for Mamdani, who had vowed to be the president’s “worst nightmare.” Is it really in his interests to participate in a rehabilitation of Donald J. Trump?

But Trump may figure, what goes down can also go up. In 2016, he cinematically launched his first presidential run by coming down the Trump Tower escalator as actors reportedly paid $50 each applauded.

Trump may now want to take the up escalator, back to the glittery New York life he once well knew.

But he would probably find, as the expression goes, that “the past is a foreign country.”