DES MOINES — When New Jersey Sen. Cory Booker (D-N.J.) came here two months ago, he lingered long after events ended to talk to the curious, posing for selfies with anyone who wanted one. After the photos blanketed the social media accounts of Iowa Democrats, Booker’s staff had them printed out, signed and mailed with a personal letter — an added touch still being talked about long after he left.

When the son of Jerry Crawford — a prominent Democratic activist who escorted Booker around the state — got married, Booker was there again, offering his congratulations in a phone call to the younger Crawford.

In ways quiet and loud, the Iowa presidential contest is already underway, 14 months before the caucuses mark the official start of the 2020 race. Candidates are lining up state directors, planning a flurry of trips in January and jump-starting the fight for an extraordinarily small slice of voters who play one of the most outsize roles in American politics.

The state Democratic Party is also on the verge of making a dramatic change to the caucus process by allowing absentee voters to participate for the first time, a move that could dramatically increase the number of voters involved and bring more moderates into a process that for decades has been dominated by the most dedicated liberal activists.

“This is a whole new ballgame,” said Norm Sterzenbach, a Democratic consultant who ran the caucuses in 2008 and is weighing whether to join a campaign this time. “The multiple candidates; running against Donald Trump; this absentee system. There’s a lot of variables and a lot of wild cards happening all at once.”

Sen. Kamala D. Harris (D-Calif.) made a recent visit with her family in tow. Los Angeles Mayor Eric Garcetti had someone conducting a round of meetings. Sen. Elizabeth Warren (D-Mass.) has been making calls to activists, passing out her cellphone number and encouraging them to call her Elizabeth.

“She’s not calling me to check on the weather out here,” said Kurt Meyer, the chairman of the Tri-County Democrats in rural northern Iowa.

The state’s Democratic activists are practically begging for a visit from the candidate of the moment, Rep. Beto O’Rourke of Texas, who reminds them of the star they launched in 2008: Barack Obama. Some have displayed “Beto” lawn signs brought back from his unsuccessful U.S. Senate campaign. So far, he has not even returned phone calls to the state — “Not even a thank you,” said one party official — in a playing-hard-to-get strategy that has increased his attractiveness but could soon approach annoyance.

“Everybody loves to kick the tires here,” said Jeff Link, a longtime Democratic consultant. “And they are dying to kick the Beto tire.”

At least four prospective candidates — Sen. Jeff Merkley (Ore.), Rep. Eric Swalwell (Calif), South Bend, Ind., Mayor Pete Buttigieg and entrepreneur Andrew Yang — were planning to attend a Thursday gathering put on by the liberal group Progress Iowa.

In a state of 3 million people, only 171,000 participated in the Democratic caucuses in 2016, so a huge amount of time and money is spent on convincing a small fraction of the state’s residents to show up. It’s also a state that is white and rural — counter to where much of the current Democratic energy arises.

“If people are serious about doing well in the caucus and they want to convey a sense to party leaders across the country they have to appeal to a broader populace to win in November 2020, they have to spend time and have some ideas that are rural specific,” said former senator Tom Vilsack, who has spoken at length with nearly every candidate considering running. “And if they don’t, and simply rely on the formula of doing well with suburban women and inner cities with minority populations, we may suffer the same fate as we did in 2016.”

As candidates begin to develop strategies — which staffers to hire, and how to balance an effort in Iowa with one in the first primary state, New Hampshire — one of the biggest variables they are confronting is the potential change in caucus voting. The state party is developing new rules to satisfy absentee voting requirements from the Democratic National Committee that are intended to allow more people to participate.

Until now, Iowa’s quirky system required participants to show up at a local precinct for a few hours on a winter’s night and organize into groups based on which candidate they support. Candidates who cannot garner 15 percent are no longer considered viable and their supporters have to pick another candidate.

How to accomplish that in a way that allows absentee participation is a major challenge. The details are still being worked out — and would need to be adopted by a state committee and approved by the DNC — but it would be a fundamental shift in how the caucuses have been conducted for decades.

One idea is to use a ranked ballot, another is to allow a proxy vote by a trusted friend or relative. Other ideas include having one dedicated precinct for all absentee ballots, or conducting a caucus over the telephone, the way it is done for military members serving overseas.

“We want to preserve what makes Iowa unique,” said Troy Price, the chairman of the state party. “Which is, you have to go out there and build relationships, and you’re making a higher-level ask: You’re asking someone to go somewhere on a night, and it’ll be cold, and it may be snowy, and you stand in front of your neighbors and . . . say, ‘This is who I want to be the next president of the United States.’ It’s different than just going into a polling booth and checking a box.”

The shift would likely mean a wider group of voters — rough estimates vary from 50 to 75 percent more — and could benefit the campaigns able to attract those who have never caucused before. It also could help moderates whose appeal extends beyond the traditionally liberal caucusgoers, or those with enough money to fund an absentee voter operation.

State party officials plan to finalize their proposal by early May, but they are conscious of any change that would make the caucus seem more like a primary. Doing so would provoke officials in New Hampshire — whose state law requires them to hold the nation’s first primary — and could trigger New Hampshire’s secretary of state, Bill Gardner, to jump in front of Iowa’s current caucus date of Feb 3.

Iowa Democrats saw mixed results during the midterm elections, but their gains were in keeping with the national party swing. Republicans maintained control of the state legislature and the governor’s office. But Democrats won two congressional seats, with Cindy Axne and Abby Finkenauer defeating incumbent Republican men. In the suburbs around Des Moines, several female Democrats defeated male Republicans in state legislative races, helping usher in a record number of women in the legislature.

“Suburbs, suburbs, women, women,” said Sean Bagniewski, chairman of the Polk County Democrats. “That’s the name of the game now. That’s the bread and butter for the Democratic Party. And it’s a sea change from where we were.”

On Saturday night, the Des Moines Register and CNN released the results of their first poll on the 2020 caucuses, showing Joe Biden in the lead with 32 percent, followed by Bernie Sanders (I-Vt.) with 19 percent, O’Rourke with 11 percent and Warren with 8 percent. Everyone else was at 5 percent or lower.

For now, the would-be candidates are sticking to the basics. Representatives of Booker and Harris have been accepting résumés and are in serious discussions with candidates to direct their Iowa campaigns.

Others are not so far along. Biden, who struggled in the caucuses in his 1988 and 2008 presidential campaigns, has little footprint in the state.

“Biden, I’m not seeing anything at all,” said one top Democrat, who spoke on the condition of anonymity to preserve relations. “When we reach out to them, it’s, ‘We’re not coming to Iowa, we’re not interested in Iowa, we have no plans to come to Iowa.”

Sen. Sherrod Brown (D-Ohio) has been calling top Iowa Democrats, seeking advice. South Carolina strategist Philip Chambers, who is working for Garcetti, spent several days in the state this month meeting with operatives.

Sen. Amy Klobuchar (D-Minn.) has reached out to potential staffers, Gov. Steve Bullock (D-Mont.) is expected again soon and Michael Bloomberg, the former New York mayor, was just in Iowa.

Pete D’Alessandro, a top aide to Sanders in 2016, could play a similar role again. But the Sanders network is splintered this time. Some are intrigued by O’Rourke. Others are entertaining Oregon Sen. Merkley or open to Rep. Tulsi Gabbard (D-Hawaii). Warren is bound to take a significant chunk.

Some in Iowa suggest Warren has lagged behind some of the other top-tier candidates in forming a state organization — in a time frame that coincided with her much-mocked release of a DNA test meant to prove she had Native American ancestry and blunt President Trump’s name-calling of her as “Pocahontas.”

Warren’s camp has consulted with several local Democrats to develop a list of people she should call. But she hasn’t been to the state in four years, and it’s clear that she has work to do.

“My thought on Warren is that her time has come and gone, to be honest with you,” said Mitch Henry, co-founder of the Asian & Latino Coalition, which has been hosting candidates and plans to make an endorsement. “That DNA test did leave a bad taste in people’s mouth. She didn’t have to prove herself to Trump. It was a bit of a fiasco.”

Rep. John Delaney of Maryland, while nationally an unknown, has done far more work in Iowa than any other candidate so far. On a recent Sunday afternoon, Penny Rosfjord, former chair of the Woodbury County Democratic Party, got a call from Warren, who said she wanted to get together when she comes to Iowa. That night, Rosfjord and a few dozen others fought snowy conditions to attend a Delaney town hall.

“People have asked me a lot about, ‘Who do you see, who looks good?’” she said. “I’m like, ‘I have no idea.’ Anything could happen . . . We have this job to do. We need to start looking, start listening and make a decision.”