Michael R. Bloomberg disrupted the Democratic presidential field on Friday as he took his first steps into the 2020 race, unnerving supporters of Vice President Joseph R. Biden Jr. and prompting Senators Elizabeth Warren and Bernie Sanders to accuse Mr. Bloomberg of seeking to buy the presidency.
But Mr. Bloomberg’s early moves also signaled he would be approaching the campaign in an unconventional manner: In a dramatic acknowledgment of his own late start in the race, Mr. Bloomberg and his advisers have decided that he would pursue a risky strategy of skipping all four traditional early-state contests in Iowa, New Hampshire, Nevada and South Carolina, and focus instead on big states that hold primaries soon afterward.
Mr. Bloomberg, who flirted with running for president in 2008 and 2016 and early this year, but had never taken a formal step to do so, filed paperwork and qualified for the Alabama primary on Friday afternoon. The Deep South state has the earliest primary filing deadline in the country, effectively forcing Mr. Bloomberg to put his name into contention this week if he did not want to get shut out of the ballot.
While Mr. Bloomberg has not made a final decision to run, his allies say he intends to enter the campaign. His consideration of a 2020 bid reflects the fluidity of the race and the angst among many leading Democrats about whether Mr. Biden is strong enough to win the nomination as a centrist standard-bearer. Mr. Bloomberg is also acting on his own longstanding ambition to be president: At 77, he is unlikely to have another chance to run if he does not attempt a campaign now.
Mr. Bloomberg’s moves have already rippled through an unsettled Democratic field. While polls show that most Democratic voters are content with their current array of candidates, there are significant pockets of unease, most of all among politically moderate donors and leaders of the party establishment who are concerned about Mr. Biden’s prospects in the primary and fear that Ms. Warren and Mr. Sanders are too liberal for the general election.
But Mr. Bloomberg will have to overcome considerable doubts across the Democratic Party about his own ability to win the nomination, and prove that he is more than a niche candidate for moderate elites.
On Friday, Mr. Bloomberg’s camp began to lay out in public a theory of how he might win the nomination: Advisers said he intended to stake his candidacy on big, delegate-rich primary states like California and Texas, where Mr. Bloomberg’s immense personal fortune could be put to extensive use.
We asked the candidates whether anyone deserves to have a billion dollars.
Howard Wolfson, an adviser to Mr. Bloomberg, said in a statement that Mr. Bloomberg would not contest the early states where other candidates have been competing for months, and would mount his candidacy in a different array of states from the outset.
“If we run, we are confident we can win in states voting on Super Tuesday and beyond, where we will start on an even footing,” Mr. Wolfson said. “But the late timing of our entry means that many candidates already have a big head start in the four early states, where they’ve spent months and months campaigning and spending money. We have enormous respect for the Democratic primary process and many friends in those states, but our plan is to run a broad-based, national campaign.”
Should Mr. Bloomberg proceed with such a campaign, he would be attempting to take a high-risk route to the Democratic nomination that has never succeeded in modern politics — one that shuns the town hall meetings and door-to-door campaigning that characterize states like Iowa and New Hampshire, and relies instead on a sustained and costly campaign of paid advertising and canvassing on a grand scale.
That approach would amount to a high-risk bet that no other candidate emerges from that early-state circuit with the kind of momentum that could overwhelm whatever operation Mr. Bloomberg has built in the Super Tuesday states that vote in early March. It is sure to alienate Democratic Party leaders and stalwarts in the early states, several of which are key battlegrounds in the general election, and intensify complaints from Mr. Bloomberg’s opponents about his reliance on personal wealth.
The plan to skip campaigning in early voting states drew a sharply negative reaction Friday night from the chairman of the New Hampshire Democratic Party, Ray Buckley.
“We are disappointed and frankly very surprised that any candidate would launch a campaign for the White House where their path doesn’t run through New Hampshire or any of the other early states,” Mr. Buckley said.
Troy Price, the chairman of the Iowa Democratic Party, criticized Mr. Bloomberg for spurning the circuit of early states that he said “makes candidates and their campaigns better prepared for a general election fight.” Iowa voters, he said, “kick the tires and ask the hard questions.”
Mr. Bloomberg’s advisers are preparing to meet several other upcoming filing deadlines, including in Arkansas. It was not clear on Friday night if Mr. Bloomberg still planned to file paperwork by next Friday to qualify for the New Hampshire primary, as he originally intended.
Many of the details of Mr. Bloomberg’s plans appeared to be coming together at the last minute. Even some of his longtime allies said they had been blindsided by Mr. Bloomberg’s sudden move to enter the race, and his advisers were reaching out to assemble staff for a presidential campaign even as Mr. Bloomberg was entering his final deliberations.
Michael Nutter, the former mayor of Philadelphia who has long been close to Mr. Bloomberg, said word of Mr. Bloomberg’s intentions had taken him by surprise on Thursday night. He said he had spoken to Mr. Bloomberg’s camp and come away convinced that Mr. Bloomberg was “serious about running.”
Mr. Nutter, who has been supporting Mr. Biden said he had not yet thought through the implications of Mr. Bloomberg’s entry for his own involvement in the race.
“I think all the other candidates will take him seriously,” Mr. Nutter said.
Mr. Biden, who appeared to have the most to lose from the sudden entry of a prominent centrist with unlimited financial resources, spoke guardedly to reporters in New Hampshire about that possibility on Friday. He called Mr. Bloomberg an “honorable guy” and deflected a reporter’s question about whether Mr. Bloomberg, who was elected mayor of New York City as a Republican and became a Democrat only last year, could be considered an authentic member of the party.
“Michael’s a solid guy, and let’s see where it goes. I have no, no problem with him getting in the race,” Mr. Biden said in New Hampshire, adding, “Last polls I looked at, I’m pretty far ahead.”
Advisers to Mr. Biden have argued in private that Mr. Bloomberg should not be overestimated as a threat to the former vice president, because he may struggle to appeal to the African-American voters and working-class whites who make up most of Mr. Biden’s political base.
Mr. Bloomberg, who is one of the country’s richest men, has his own vulnerabilities, such as his support for stop-and-frisk policing and charter schools, and his opposition to liberal economic policies that involve taxing large private fortunes and breaking up banks and other big corporations.
President Trump, for his part, did not sound concerned about Mr. Bloomberg on Friday morning. Mr. Trump noted that Mr. Bloomberg would spend a lot of money on a campaign and predicted he would damage Mr. Biden in the process. Speaking in the terms of derision he usually applies to political rivals, Mr. Trump said without elaborating that Mr. Bloomberg had “personal problems” and applied a derisive nickname.
“There’s nobody I’d rather run against than little Michael,” Mr. Trump said.
Ms. Warren and Mr. Sanders have already begun to take on Mr. Bloomberg more assertively, both emailing their supporters to warn that a prominent billionaire was seeking to — as they put it — buy the presidency. “The billionaire class is scared and they should be scared,” Mr. Sanders tweeted on Thursday evening, without mentioning Mr. Bloomberg by name.
Campaigning in Raleigh, N.C., on Friday, Ms. Warren avoided attacking Mr. Bloomberg directly but told reporters that a candidacy funded from personal wealth would not produce “a government that works for the people.”
“I don’t think that big money ought to be able to buy our elections, and that’s true whether we’re talking about billionaires or corporate executives that fund PACs or big lobbyists,” Ms. Warren said.
Mr. Bloomberg initially decided last winter that he would not challenge Mr. Trump in 2020, in large part because he concluded he could not win the Democratic nomination with Mr. Biden in the race, as a formidable standard-bearer for the party’s moderate wing. But Mr. Biden’s struggles in recent months have given Mr. Bloomberg new optimism that there is space for him in the campaign.
There is considerable skepticism among the leading Democratic candidates about Mr. Bloomberg’s path forward in a 2020 primary. A centrist business mogul in his eighth decade, he would be seeking to lead a party focused on questions of economic inequality, cultural diversity and generational change. (The 2020 field already has several candidates in their 70s: Mr. Sanders is 78, Mr. Biden is 76, Mr. Trump is 73 and Ms. Warren is 70.)
But unlike the rest, Mr. Bloomberg has never run a political campaign outside New York City, and he has neither a sweeping progressive platform, like Ms. Warren and Mr. Sanders, nor a famous friendship with the first black president, like Mr. Biden, to excite the Democratic base.
A political nomad with respect to party affiliation, Mr. Bloomberg was elected mayor three times on the Republican ticket before he registered as a Democrat during the midterm elections and spent more than $100 million to help the party take control of the House of Representatives.
Former Senator Bob Kerrey of Nebraska, a moderate who has endorsed Mr. Biden, said he believed Mr. Bloomberg had the potential to cut into Mr. Biden’s electoral coalition.
“I very much would like to see Joe Biden be president, but if Mike Bloomberg was the nominee of the Democratic Party, would I be disappointed?” Mr. Kerrey said. “Not in the slightest.”
Other supporters of Mr. Biden were more dismissive.
“There’s not a snowball’s chance in hell of him getting the nomination,” said John Morgan, a Florida trial lawyer who is raising money for Mr. Biden. “He’s a Republican billionaire.”
Alexander Burns reported from New York and Katie Glueck from Concord, N.H. Thomas Kaplan contributed reporting from Raleigh, N.C.