Bloomberg said himself in the past that he viewed the Democratic field as too crowded to make it possible to win. Now he’s evidently decided that former Vice President Joe Biden is too weak and fading, and that none of the other challengers have what it takes to wrest the nomination from progressive Sens. Elizabeth Warren (D-Mass.) and Bernie Sanders (I-Vt.).

“This is for real. It is now or never, and he chose now,” a person close to Bloomberg said Thursday night as news of Bloomberg filing for the Alabama primary broke. “A combination of Biden sinking and Warren rising motivated him to take a shot. At heart, he is a patriot and is really concerned with where the country is heading and what happens if the Democrats don't have a strong nominee.”

This person added: “Warren as the nominee equals four more years. All the polling supports that. So he is going to make a run at it and the chips will settle where they may. He has the resume and the checkbook and is willing to run.”

There is no question about the checkbook.

Bloomberg has a net worth of about $53 billion and longtime operative friends like Kevin Sheekey to help him get into debates, get on ballots and come up with some kind of legitimate plan.

But his generally moderate economic views coupled with his deep lifetime ties to Wall Street’s top banks and senior executives makes him an easy target for candidates like Warren who on Thursday night dismissed his candidacy. “I think what we ought to do is, we ought to be building a grassroots movement to make real change in this country,” she said. “I don’t think that democracy should be about people coming in and buying elections.”

One senior Wall Street executive who is generally supportive of Biden’s candidacy — but worried, as many are, about the former vice president’s fundraising numbers and poll standing in early states — suggested they thought a Bloomberg win wasn’t impossible, but still highly unlikely.

“It was smart of him to wait and not look overeager [and] taking advantage of not having to raise money,” this executive said. “At this point, his natural constituency — moderate Dems, suburban families — are practically begging for someone to support. And the serious work he’s done on climate and guns will help with a lot of folks across the country.”

But this person added: “It’s still a heavy lift. Natural target for the socialist lefties, late to organize in early primary states, no strong base with African American voters, no natural constituency outside the coasts. No clear path. But the New York finance crowd will be delighted to have someone they can support wholeheartedly. Probably hurts Mayor Pete [Buttigieg], who was becoming their darling.”

A Bloomberg run, while perhaps boosting Warren and Sanders and diluting support for Biden, could in fact be a blow to Buttigieg, who was crafting a successful rise as a socially progressive voice who is also concerned about not going all-in for hugely expensive programs like "Medicare for All" and the Green New Deal.

He’s attracted lots of money and attention from younger people in the finance community, helping build a war chest that stood at $23.4 million at the end of the third quarter, just behind Warren and Sanders and well above Biden’s $8.9 million.

Buttigieg actually learned of Bloomberg’s apparent entry into the race while leaving one of four New York City fundraisers on Thursday, according to a person familiar with the event. He did not have any big reaction to the news.

Buttigieg backers think he will continue to raise money with relative ease even with Bloomberg in the race and will continue to build out large organizations beyond Iowa and New Hampshire in states like Nevada, South Carolina and California.

And they think once Bloomberg gets in, the former mayor, who famously does not love retail campaigning, will find it enormously hard to get any real traction.

Rival campaigns are already compiling opposition research documents on Bloomberg to deploy if the former New York City major actually fully jumps into the race. They expect to describe him as a candidate of the top 1 percent who registered very low in early surveys that included him as a possible candidate. They will bring up problems on “stop and frisk” that could be major stumbling blocks with African Americans who make up a key Democratic primary constituency. They will bring up issues with women suing Bloomberg LP over discriminating against pregnant employees. And that’s just the beginning.

And the senior Wall Street executive backing Biden — the one who said he’d be “shocked“ if Bloomberg were in the race in 45 days — said the former mayor is dramatically overstating how weak the former VP really is. “He’s been getting beat up for weeks and weeks, and yes, his debates are clumsy. But he’s still at 30 percent nationally. People like Joe Biden and they trust him. And frankly, I think the Warren people would have paid Bloomberg to get in the race. It’s the best thing that could happen to them.”