MASON CITY, Iowa — With just under two months until the Iowa caucuses, the already-volatile Democratic presidential race has grown even more unsettled, setting the stage for a marathon nominating contest between the party’s moderate and liberal factions.
Pete Buttigieg’s surge, Bernie Sanders’s revival, Elizabeth Warren’s struggles and the exit of Kamala Harris have upended the primary and, along with Joseph R. Biden’s Jr. enduring strength with nonwhite voters, increased the possibility of a split decision after the early nominating states.
That’s when Michael R. Bloomberg aims to burst into the contest — after saturating the airwaves of the Super Tuesday states with tens of millions of dollars of television ads.
With no true front-runner and three other candidates besides Mr. Bloomberg armed with war chests of over $20 million, Democrats are confronting the prospect of a drawn-out primary reminiscent of the epic Clinton-Obama contest in 2008.
“There’s a real possibility Pete wins here, Warren takes New Hampshire, Biden South Carolina and who knows about Nevada,” said Sue Dvorsky, a former Iowa Democratic chair. “Then you go into Super Tuesday with Bloomberg throwing $30 million out of his couch cushions and this is going to go for a while.”
That’s a worrisome prospect for a party already debating whether it has a candidate strong enough to defeat President Trump next November. The contenders have recently begun to attack one another more forcefully — Ms. Warren, a nonaggressor for most of the campaign, took on Mr. Buttigieg on Thursday night — and the sparring could get uglier the longer the primary continues.
A monthslong delegate battle would also feature a lengthy public airing of the party’s ideological fissures and focus more attention on contentious policies like single-payer health care while allowing Mr. Trump to unleash millions of dollars in attack ads portraying Democrats as extreme.
The candidates are already planning for a long race, hiring staff members for contests well past the initial early states. But at the moment they are also grappling with a primary that has evolved into something of a three-dimensional chess match, in which moves that may seem puzzling are taken with an eye toward a future payoff.
Ms. Warren and Mr. Sanders, for example, are blocking each other from consolidating much of the left, but instead of attacking each other the two senators are training their fire on Mr. Buttigieg, the South Bend, Ind., mayor. He has taken a lead in Iowa polls yet spent much of the past week courting black voters in the South.
And Mr. Biden is concluding an eight-day bus tour across Iowa, during which he has said his goal is to win the caucuses, but his supporters privately say they would also be satisfied if Mr. Buttigieg won and denied Ms. Warren a victory.
It may seem a little confusing, but there’s a strategy behind the moves.
Mr. Sanders and Mr. Warren each covet the other’s progressive supporters but are wary about angering them by attacking each other. So Ms. Warren has begun drawing an implicit contrast by emphasizing her gender — a path more available now with Ms. Harris’s exit — and they are both targeting a shared opponent whom many of their fiercest backers disdain: Mr. Buttigieg.
The mayor has soared in heavily white Iowa, but has virtually no support among voters of color. So he started airing commercials in South Carolina spotlighting his faith and took his campaign there and into Alabama this past week — an acknowledgment that Iowans may be uneasy about him if he can’t demonstrate appeal with more diverse voters.
As for Mr. Biden, his supporters think he would effectively end the primary by winning Iowa. But they believe the next best outcome would be if Mr. Buttigieg fends off Ms. Warren there to keep her from sweeping both Iowa and New Hampshire and gaining too much momentum. They are convinced she’s far more of a threat than Mr. Buttigieg to build a multiracial coalition and breach the former vice president’s firewall in Nevada and South Carolina.
Meanwhile, no other hopeful is drawing more chatter in Iowa as a compromise choice among moderates than Senator Amy Klobuchar, who has spent more time in the state than any of the top candidates.
Taken together, the shadowboxing, bank shots and sheer uncertainty of it all reflect what a muddle this race has become. Besides the party’s unifying hunger to defeat Mr. Trump, the only clarity is the rigid divide among voters along generational, ideological and racial lines.
These fractures could ensure different outcomes in the first four nominating states — mostly white Iowa and New Hampshire and more diverse Nevada and South Carolina — going into Super Tuesday on March 3.
That’s the day on which Mr. Bloomberg is staking his candidacy, when 14 states are up for grabs. The former New York mayor, a political centrist, is skipping the early states and pouring tens of millions of his money into Super Tuesday in hopes that the field remains split by then or that one of the progressives is pulling away.
If he gains traction, that could augur a primary that may not be over by the time the party gathers in Milwaukee next summer for its convention.
Of course, it’s hardly a forgone conclusion that the Democratic contest will drag on. The front-loaded calendar means that if one candidate does rattle off early victories, he or she will be able to amass a fearsome delegate advantage.
The last time the party confronted such an uncertain primary, in 2004, John Kerry revived his campaign shortly before voting began and captured Iowa and New Hampshire, allowing him to quickly secure the nomination.
Yet no candidate today may prove capable of extinguishing the embers of the primary the way Mr. Kerry did. Four candidates — Mr. Sanders, Ms. Warren, Mr. Buttigieg and Mr. Bloomberg — are well funded or enjoy reliable streams of money.
Perhaps more significantly, the divisions in the party are now wider than they were in the previous decade, with opposing ideological factions far less willing to settle.
Nowhere is the Democratic race more fluid than in Iowa, where 70 percent of caucusgoers said in a Des Moines Register-CNN poll last month that their minds were not made up.
Mr. Buttigieg emerged atop the field in the survey, but he is now under attack on multiple fronts.
Ms. Warren is assailing him for not being more transparent about his donors, Mr. Sanders is targeting him for not offering a more expansive free college proposal, and a super PAC supporting Senator Cory Booker is on the air in Iowa favorably contrasting Mr. Booker to Mr. Buttigieg.
And Iowa allies of his rivals are taking on Mr. Buttigieg even more aggressively.
“Mayor Pete is vanilla ice cream,” said Claire Celsi, an Iowa state senator supporting Ms. Warren. “He’s just somebody that people can agree on, but the problem is that we live in a way more complicated world than that.”
The former Iowa governor Tom Vilsack, who is backing Mr. Biden, likened Mr. Buttigieg to a Democrat many in the party would just as soon forget.
“He reminds me of, not in terms of character, but in terms of people reacting to him, as John Edwards in 2004,” Mr. Vilsack said. “He’s something new, he’s a comer.”
Lis Smith, an adviser to Mr. Buttigieg, said the attacks were a result of voters “gravitating toward his campaign.”
“They can attack Pete all they want, he’s going to be laser focused on talking about why he’s the best person to bring this country together on Day 1 of a post-Trump presidency,” she said.
But Mr. Buttigieg’s campaign recognizes how urgently he must broaden his coalition — and prominent Democrats have nudged the campaign to focus less on the details of his plans for black voters and do more to emphasize his Christianity and military service. He is now up on television in South Carolina quoting scripture and in Iowa with a spot that features an African-American veteran recalling their service.
Mr. Biden is counting on these efforts to fall short and for Mr. Buttigieg to meet the same fate of previous Democratic hopefuls who lost because they could not expand their support beyond upscale white voters.
“There is no one else who is in a position to all of a sudden to do what Barack was able to do,” Mr. Biden told reporters this past week, suggesting that Mr. Buttigieg would not gain support with black voters by winning Iowa, as Mr. Obama did in 2008.
Ms. Warren is less inclined to discuss tactical matters, but her recent moves reflect a candidate very much concerned about the direction of the race.
She has drastically cut her stump speech, leaving more time for questions from voters, and after saying for months that she does not want to criticize her fellow Democrats she is now confronting Mr. Buttigieg over his high-dollar fund-raising.
Just as striking, she is taking more overt steps to highlight her history-making potential. After Ms. Harris dropped out, Ms. Warren sent a fund-raising email noting that “two women senators,” Ms. Harris and Kirsten Gillibrand, “have been forced out of this race while billionaires Tom Steyer and Michael Bloomberg have been allowed to buy their way in.”
Addressing voters in Iowa City, Ms. Warren announced to booming applause that she planned to wear a pink Planned Parenthood scarf at her presidential inauguration and in a discussion about her plans won cheers for another reference to her gender.
“I will do everything that, oh, I love saying this, a president can do all by herself,” Ms. Warren said.
What has been puzzling to her rivals, though, is what she has not done as a candidate: namely, spend more money on advertising in Iowa.
She ceded the airwaves here to rivals like Mr. Sanders and Mr. Buttigieg for all of October, and her spending in November was less than half of theirs, according to Advertising Analytics, an ad tracking firm.
Ms. Klobuchar has also not had much of an advertising footprint, but many Iowa Democrats believe she is the most likely candidate to make that late push.
Strolling into a Des Moines coffee shop recently, Connie Boesen, a city councilor, pronounced that she was leaning in Ms. Klobuchar’s direction because “she’s realistic,” a reference to the senator’s moderate politics.
For many Democrats, especially those in Northern Iowa, the Minnesota senator is a familiar figure who has more experience than Mr. Buttigieg but is not as old as Mr. Biden.
Asked who they were considering after a Biden town hall meeting this past week, three voters from outside Mason City all cited Mr. Biden and Mr. Buttigieg — but also added a third name: Ms. Klobuchar.
Sydney Ember contributed reporting from Des Moines and Reid Epstein from Washington.