“Watch for smoke signals from Chappaqua,” a Democratic friend said recently. “She wants back in.”

She — there is only one political she — might be getting what she wants.

The report that Hillary Clinton could become Michael Bloomberg’s running mate is one of those times when it is no exaggeration to use the word bombshell. Earthquake would also work, assuming the political marriage actually happens.

For now, it’s a trial balloon, as demonstrated by the timing and the way the idea was leaked. A big red banner on the Drudge Report blaring “EXCLUSIVE” is designed to shock and awe the political system, then gauge the fallout.

Bloomberg, remember, is a numbers guy and his team conducts polls relentlessly. Drudge says they’ve already tested the tag-team idea quiet­ly and, liking what they saw, now want to go public and test it more broadly.

It won’t take long to figure out which way the wind is blowing. It is such a big, bold stroke that, while it comes out of the blue, the public ­reaction will be swift.

My guess is that this marriage of convenience gets consummated fairly quickly. Bloomberg needs immediate help to win the nomination, with March a make-or-break month.

Clinton, as the world knows, is desperate to get revenge on Donald Trump and will almost certainly seize another chance at the White House, even if it means being relegated to standby equipment.

While Bernie Sanders and his committed clan will be loud exceptions, enough Democrats, I believe, will support a Bloomberg-Clinton ticket as the best chance to defeat Trump.

If all that comes to pass, the general election would be a combustible clash that will make the 2016 election look like a walk in the park. It won’t exactly be a Trump-Clinton rematch, but close enough that the faint of heart should start searching for safe and quiet refuge.

Clinton, of course, is a human lightning rod and her relationship to voters is obviously complicated. The 2016 results perfectly captured the love her/hate her split, as she won the popular vote but lost the Electoral College.

It was her second defeat, with Barack Obama besting her in the 2008 primaries, and it looked as if her political obituary was complete. Her disgraceful whining that Russia helped Trump steal the election marked her as a sore and bitter loser and even among her fans there has been little appetite for a third Oval Office run.

Although she and her camp dropped hints that she was not closing the door, no Draft Hillary movement emerged.

Instead, in the three years since Trump shocked the world by beating her, Democrats had moved on. In her absence, some 25 candidates sought the 2020 nomination, and there were no pilgrimages spotted at her home in Chappaqua seeking her endorsement.

Even more infuriating, Sanders, her unforgiven arch­rival from 2016, has become the front-runner.

And now comes Bloomberg, offering to save her from boredom and ignominy. It’s not an offer she can refuse.

His reasons are pure business and driven by math. The former New York City mayor’s bid for the presidency is unique beyond measure, as is his fortune, but time is not his friend.

He started late and had the unorthodox idea of skipping the first four states while pouring hundreds of millions of dollars worth of ads and staff into the Super Tuesday states that vote on March 3.

Bloomberg’s aim has been clear — become the so-called moderate alternative to Sanders and his socialist agenda. Mr. Moneybags has shown some life in recent polls, and the decline of Joe Biden has opened a space for him.

However, the surprising rise of Amy Klobuchar and Pete Buttigieg has complicated his path forward and forced him to do something dramatic. Inviting Clinton to join him would be the ultimate Hail Mary and immediately change the conversation about him, which has been mostly focused on his wealth and his racially tinged comments about stop-and-frisk and redlining.

In fact, he needs an outsize haul of delegates in a hurry or he’ll run out of time and states where he could win enough support to have a realistic chance of being the nominee.

Consider that some two-thirds of pledged delegates will have been awarded by the end of March. Bloomberg’s best hope — prevailing at a brokered convention — depends on having something reasonably close to the 1,991 delegates needed for a majority on the first ballot.

Starting with a second ballot, when 771 super delegates can also vote, the minimum needed to win grows to 2,375 delegates.

A final clincher for Bloomberg among primary voters could be Obama’s blessing. As I wrote last week, the former president has let it be known he wants to stop Sanders, and endorsing Bloomberg was emerging as a logical possibility.

The two men have supported each other in the past and while their policies are not identical, there would be no major differences, certainly in these circumstances. Obama, too, would love nothing more than to help end Trump’s presidency.

If the Clinton proposal comes to fruition and gives Bloomberg an instant boost, expect Obama to move quickly to help secure the nomination.

So the wedding planners have been alerted and, if bride and groom make their deal, a lavish affair will soon commence. Fortunately for the groom, he can afford an endless number of food ­tasters.

De B all yours, Bernie!

The news that Mayor Bill de Blasio is going to start campaigning for Bernie Sanders is New York’s gain and Sanders’ loss.

For the first time in modern history, the mayoralty has become something close to a no-show job. Even when he’s in town, de Blasio is usually missing in action at important times, such as during the recent disruptions of the transit system by far-left hooligans.

When he does show up, it’s merely to throw ever more gobs of money at problems and pretend he has fixed everything.

The oddity is that it’s now clear he only wanted the job as a political stepping­stone. In reality, being mayor is the best job he’ll ever get and he threw it away with displays of ingratitude and indifference.

Bernie can have him.

A pass for FBI liar

Andrew McCabe won’t be prosecuted.

Of course he won’t. A perk of being former deputy FBI director is that you’re too big to jail, no matter how many times you lie under oath.