MARSHALLTOWN, Iowa — On a trip to Iowa in June, Senator Bernie Sanders confided in aides about a central gamble of his second bid for the White House.
As nearly two dozen other presidential candidates and their supporters were heading to an Iowa Democratic Party dinner, the first major event of the 2020 election cycle, Mr. Sanders was on his way to march with striking fast-food workers. While such populist gestures have defined Mr. Sanders’s life in politics, he was taking a risk in favoring grass-roots organizing over the party politicking usually essential to winning the Iowa caucuses, as he acknowledged in a car ride to the protest.
“This is going to be hard,” he said, according to an aide who was present. “But,” he said, using a profanity for emphasis, “this is the only way we’re going to do it.”
Every top Democratic candidate has been making calculations to try to win Iowa’s first-in-the-nation caucus, and, lately, many have been staking their candidacies to a big result on Feb. 3. But Mr. Sanders stands out in several ways: He nearly won Iowa in 2016 against Hillary Clinton and, some allies say, he cannot afford to be anything less than a close runner-up again.
He is returning to the state this week after suffering a heart attack that stirred questions about his campaign’s viability. He has the most money in the race but also faces tough competition for liberal voters from a leading Iowa candidate, Senator Elizabeth Warren.
And, as his solidarity with the fast-food workers showed, he is trying to strengthen his base of voters by dedicating time and resources to wooing workers, young people, Latinos and others in Iowa, rather than focusing on winning over more party leaders. It is something of a shift from 2016, when Mr. Sanders and his allies were a greater presence at Democratic Party dinners and events to try to compete with Mrs. Clinton.
Increasingly, Mr. Sanders and his allies are making it clear that he is determined to win Iowa, even as he faces an uphill battle with about 100 days to go before the caucuses.
“I’m here this evening to ask for your help,” he said at a town hall-style event in Marshalltown on Thursday. “I don’t have to tell anybody in this room that Iowa plays a very disproportionately large role in the political process.”
Mr. Sanders continues to lag Ms. Warren and former Vice President Joseph R. Biden Jr. in polls. As candidates like Pete Buttigieg, the mayor of South Bend, Ind., nip at his heels, his campaign has zeroed in on Iowa, viewing it as critical to his chances of winning the Democratic nomination, according to several people familiar with his strategy. Some advisers say a strong showing in Iowa — especially if he finishes ahead of Ms. Warren — would be enough to catapult him through New Hampshire and into Nevada and Super Tuesday.
“Iowa has to be a top priority for the campaign — we need to do very well in the state,” said Representative Ro Khanna, one of Mr. Sanders’s national campaign co-chairs.
“I hope he can go there every week,” Mr. Khanna said. “He needs to be in Iowa as much as possible.”
To that end, his campaign has recently reallocated resources to the state, including spending $1.3 million to air its first television ad this month. It has built out its Iowa team, naming a key communications aide as its deputy state director. The campaign has also expanded its ground operation, with 13 field offices and more than 110 paid staffers.
Mr. Sanders returned Thursday for a two-day, five-event swing, and plans to be back next week to lead a “march to end corporate greed.” According to aides, his campaign is also discussing a trip to the state with Representative Alexandria Ocasio-Cortez, who recently endorsed him.
Mr. Sanders, however, has competition: Nearly all of the top-tier candidates have also signaled that Iowa is a top priority.
Mr. Biden’s campaign has publicly sought to lower expectations but he has been to the state three times this month and is planning another four-day swing there next week. Ms. Warren, whose campaign was among the first to establish a presence in the state, has 19 field offices. Mr. Buttigieg recently completed an Iowa bus tour. Senator Amy Klobuchar of Minnesota has made 21 trips to the state, including her own post-debate bus tour, and has visited 55 of the state’s 99 counties. Senator Kamala Harris vowed to visit the state every week in October.
The sudden flurry of attention represents a change from earlier this year, when White House hopefuls appeared to be embracing a more national campaign strategy that took them beyond Iowa and other early nominating states. The growth of social media, the changes to the electoral calendar and the increasing diversity of the Democratic electorate combined to make it seem like Iowa, a predominantly white state, might lose its sway in the primary process.
“Usually there’s a ramp-up period in past presidential cycles,” said Sean Bagniewski, the Democratic chair in Polk County, about the focus on Iowa. “This year, it was like a thunderclap.”
The stakes in Iowa for Mr. Sanders have personal and psychological dimensions. After his surprising performance in the caucuses in 2016, some aides said the state has taken on an almost mystical quality. A weak result could also indicate that he does not have the same influence with progressive voters as he used to.
Despite a series of disappointing polls in the state — a Suffolk University/USA Today poll released this week showed him in fourth place — allies are confident he is still in a position to do well.
Like it did in 2016, the Sanders campaign is betting on an extensive ground game that relies heavily on a vast network of volunteers that they hope will motivate other supporters to turn out on caucus night — including people who do not typically participate in the political process.
His aides believe that the technique, known as distributed organizing, will help motivate unlikely or first-time caucusgoers, especially those who were too young to participate in the last presidential caucuses; Latino voters, whose turnout rate in the caucuses is typically low; and working-class voters. The campaign sees high potential for victory particularly in and around college towns, like Ames and Iowa City, and in rural areas.
To solidify his base of support, he has spent hours rallying on college campuses in an effort to capture the support of young voters. He has courted labor support particularly in counties along the Mississippi River. And he has held multiple “Unidos con Bernie” events with Latino voters.
With $33.7 million cash on hand at the beginning of October, he will likely have plenty of money to spend in the state going forward on staffing and advertising. (On Friday, his campaign plans to go on air with an upbeat new television ad, about climate and green jobs in Iowa.)
Aides are sensitive to any comparison of the Sanders campaign of 2020 to the Sanders campaign of 2016: Unlike then, when voters only had to choose between him and Mrs. Clinton, they now have a wealth of options. To win in Iowa this cycle, he need only secure a larger percentage of the vote than his opponents.
But he has struggled to expand his support in the state, and there are some signs it may be diminishing: According to a poll last month from The Des Moines Register and CNN, only 25 percent of those who say they caucused for Mr. Sanders in 2016 said they would do so again, while 32 percent said they would support Ms. Warren and 12 percent said they would support Mr. Buttigieg.
In recent months, Mr. Sanders has begun holding smaller town hall-style events that give audience members the opportunity to share their own deeply personal stories. Advisers hope the events will inspire voters to work together to change what Mr. Sanders views as a broken system. (The campaign recently cut a television ad from one of these town halls in Iowa that featured a woman telling a horrific story about medical debt.)
Mr. Sanders is staking his success on supporters like Morgan Baethke, 58, of Indianola, Iowa, who was one of about 100 people who came to hear him speak in Marshalltown, the first stop on a two-day “end corporate greed” tour.
Mr. Baethke, who works in retail, said he tries to convince other voters to caucus for Mr. Sanders by knocking on doors and participating in parades and festivals.
But he also revealed a fundamental tension endemic to the Sanders campaign’s organizing strategy: He said that he prefers to speak to voters in a neighboring county rather than his own.
“I don’t feel comfortable in my home county looking at customers who I deal with during the day, going to their house in the evening, knocking on their door and saying, ‘Would you support Bernie Sanders?,’” he said.
Katie Glueck contributed reporting from Muscatine, Iowa, and Thomas Kaplan from Waterloo.