Bloomberg’s data gurus first noticed a sharp uptick in Democrats’ obsession with unseating Trump around Sept. 20. That’s when news broke that the president appeared to improperly threaten to withhold aid to Ukraine if the country didn’t open an investigation into Biden and his son Hunter.

Democratic leaders nationally embraced impeachment, and so did Bloomberg. He had been opposed to impeachment but then started to see a path to the nomination open for him — albeit an unorthodox one in which he would focus on the Super Tuesday states and largely bypass the crucial first four voting states.

“The data shifted after impeachment. Democrats were always focused on electability, but after Ukraine that impulse became even stronger. And the current field is not well-poised for success,” said Bloomberg’s adviser, Howard Wolfson, in explaining how the collision of forces caused Bloomberg to rethink his decision not to run.

Also forcing Bloomberg’s hand were the early qualifying dates for presidential candidates to get on next year’s ballots in states like Alabama and Arkansas. His team put his name in as a fail-safe insurance policy because it was now or never for Bloomberg, who considered presidential bids in 2008 and 2016 as well.

Worth $53 billion, Bloomberg would spend no time hitting up donors. And whether he runs or not, Bloomberg still has a $500 million plan to take out Trump.

In a sign of the seriousness of his potential bid, Bloomberg’s foundation office in Manhattan switched its TVs on Friday from his eponymous news network to left-leaning MSNBC.

But if Bloomberg, the man who invented an entire computer system to decipher financial markets, is such a numbers wonk, his many skeptics wonder about the math underpinning his potential candidacy.

He’s a billionaire and former Republican in a primary fueled by progressive energy and suspicion about wealth and conservatism. He’s an old, white New York technocrat who isn’t known for an electric speaking style in a party that yearns for the next Barack Obama. And he has potential problems with black voters after his stewardship of a police department that employed stop-and-frisk policing, which disproportionately targeted minorities.

He continued to defend the practice, which a judge ruled unconstitutional, even as his administration began reversing course on it.

Bill Burton, a former Obama campaign adviser, said he couldn’t understand Bloomberg’s path, saying it could not be paved with enough billions to carry him across the finish line.

“Bloomberg was previously able to overwhelm opponents with millions in relentlessly positive advertising,” Burton said. “The question today is whether that will be enough to take on the energy behind 40 percent of Democrats who support [Elizabeth] Warren and [Bernie] Sanders or the challenges for him in the African American community.”

If Bloomberg decides to run — and it’s still an if — he won’t merely face the challenge of growing a constituency overnight. He has to contend with the complications of the primary map and calendar. At this stage, Bloomberg is not planning to campaign hard in any of the early states: Iowa on Feb. 3, New Hampshire on Feb. 11, Nevada on Feb. 22 and South Carolina on Feb. 29, according to an adviser. In fact, the person said Bloomberg is leaving open the possibility that he may not contest some of them — or all.

Current polls show Warren leading in the first two states, and Biden in the latter two. If each wins in those four states as polls now indicate, it would likely winnow the field to a two- or three-person race heading into Super Tuesday on March 3, when 16 states vote.

That’s when Bloomberg would essentially start campaigning in earnest in undesignated states, the adviser said.

Biden aides counter that the former vice president is well positioned from Nevada’s caucus through Super Tuesday because he dominates among African American voters, and some polls show he also leads among Latinos. That could give him a major edge in collecting the delegates needed to clinch the nomination.

“About two-thirds of the delegates awarded in Nevada, South Carolina and Super Tuesday come from states where at least 40 percent of the Democratic primary vote will come from communities of color,” a top Democratic strategist and Biden booster who has advised the campaign said in a text message to POLITICO. By contrast, the person said, “Communities of color are 8-10 percent in Iowa and New Hampshire.”

“Unless there is something I’m missing, I don’t really see where his [Bloomberg’s] candidacy changes the current calculus after the first two states.”

Wolfson, Bloomberg’s top political adviser, wouldn’t discuss the former mayor’s specific poll numbers. When he opted not to run in March, Bloomberg was polling at just 2 percent in the crowded field. Also, about as many Democrats had a favorable impression of him as an unfavorable impression.

But Wolfson said Bloomberg’s poll numbers have risen since then. And his camp believes that Bloomberg’s history as a longtime philanthropist, successful businessman, media mogul and major financier of the climate change and gun control movements will play well with voters and yield grassroots support.

Wolfson said he understood all the criticisms of Bloomberg’s path. But he ticked off data points he predicted would appeal to any voter: “Self made. Highly successful businessman and three-term mayor of the country’s largest city. Jobs creator. And record-setting philanthropist who has spent billions taking on the NRA, Big Tobacco, and coal companies and putting lower-income kids through college.”

Also, Bloomberg views Biden as less formidable than he was when the mayor decided not to enter the primary earlier this year.

“What has changed is that Biden has not run a particularly good campaign. I’m not sure anyone outside the Biden world would disagree with that. I’m not sure anyone inside the Biden world would disagree with that if they’re being honest," former Bloomberg adviser Bradley Tusk said in an interview. “[Biden’s] fundraising numbers obviously were not encouraging [for Biden].”

While he believes he can beat Trump, Tusk said, Bloomberg recognizes the difficulty in winning over the left wing of the party, particularly given his ardent defense of Wall Street and capitalism. Bloomberg is also aware that Elizabeth Warren is ascendent, but is “especially concerned” that she cannot defeat Trump, added Tusk.

Bloomberg kept his plans under wraps this week, when he hosted a swanky reunion party for former city employees in the Manhattan offices of Bloomberg Philanthropies — the charity from which he funds national and global efforts to reduce smoking, combat climate change and increase college enrollment.

Instead, he made a self-deprecating speech that was largely devoid of national politics, a former aide who attended told POLITICO.

“Bloomberg people are always more bullish on Mike running for president than everyone else is. So there were plenty of people in the room who were really excited about [the possibility of] Mike running for president,” the attendee, a former aide to Bloomberg, said. “He liked Biden. He’s been surprised at Biden’s implosion,” said the former aide, who asked not to be identified.

Bloomberg is also keenly aware that at 77 years old, this is likely his last chance to run. “I think he thinks that this is it. That is a factor. There’s no next time," the person added.

A top Bloomberg adviser who was not authorized to speak on the record said the most recent poll Bloomberg paid for showed there is a real and growing opening for him.

“He saw the data showing Democrats see Trump as more dangerous than ever and you could actually see the look on his face as he took it in,” the adviser said. “The arguments for his candidacy are getting stronger: Trump is more dangerous and the electorate is more practical.”