Cory Booker secured the first legislative endorsement of the Iowa caucus cycle. Kamala Harris put together "Camp Kamala" sessions to mobilize university students. Elizabeth Warren created a lineup of events, including a "Pints and Persist" happy hour, to woo Iowa wonks. And Bernie Sanders’ staff says they have identified nearly 20,000 volunteers in Iowa.

The on-the-ground Iowa organizing, perhaps even more than the high-profile candidate events, will boost Democratic presidential candidates in preparation for the 2020 caucuses. Campaign leaders and caucus activists say the crowded field puts an even higher premium on organizing and relationship-building than in past cycles.

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“These teams now are working those (voter) lists, reaching out, building relationships with key Democrats and are planning to be in a position to take advantage when Iowa Democrats start to commit,” said Matt Paul, a Democratic operative who is not aligned with a campaign this cycle and who ran Hillary Clinton’s 2016 Iowa operation.

“When this race comes into a little better focus, well-organized campaigns are positioned to take advantage of that," he said.

Clinton launched her presidential campaign on April 12, 2015, and by July of that year, her team had hired 47 paid staffers. This year's candidates are already on pace to surpass that.

Warren, who was among the first to announce an exploratory committee in late December, has already hired a staff of nearly 50 people, giving her the state’s largest field operation to date. That number includes an organizing director, two deputy organizing directors, eight regional organizing directors and 20 field organizers who are stationed across Iowa.

Former congressman John Delaney of Maryland, who has been running since October 2017, hired his first Iowa staffer in September of that year and has grown his footprint to 25 full-time staffers today. Booker has hired 16 people in Iowa and plans to add 25 more full-time paid staffers in the next couple of weeks. Vermont Sen. Bernie Sanders has brought on seven Iowa staffers, and Harris has five on the ground here.

All say they will continue adding to their ranks in the coming weeks and months.

Organizing key, but not everything

But, as Clinton’s 2016 campaign showed, a large Iowa staff can only get a candidate so far.

Clinton's widely praised organizing efforts helped her to beat out Sanders on caucus night in Iowa — but just barely. Enthusiasm among young people and independents fueled the Vermont senator’s insurgent rise and helped propel him to success in other states.

Warren, a Massachusetts senator, has hired the most staffers in Iowa and launched a robust organizing effort, but has had to deflect criticism that her fundraising has lagged behind others’.

Booker, who plans to soon have 41 on-the-ground staffers, has had lackluster results in early polling.

Other candidates in the massive field of 18 Democrats have fueled voter interest and impressive national fundraising hauls without robust campaigns on the ground. Neither South Bend, Indiana, Mayor Pete Buttigieg, who is expected to formally announce his campaign soon, nor former Texas congressman Beto O'Rourke, have huge campaign infrastructure in the first-in-nation caucus state.

O'Rourke has hired a handful of staffers who are making an aggressive push for more, and Buttigieg has hired one outreach coordinator in Iowa.

But Paul, formerly of the Clinton campaign, cautioned that campaigns need an infrastructure in place to convert those viral or breakout moments into lasting support.

“They need to give people who are seeking information or who want to sign up a place to go, a place to engage, so that you have the ability to have follow-up conversations with them digitally and in person,” he said.

Mike Frosolone, Booker’s Iowa state director, said the campaign is investing early in its organizing staff so that it can be ready if Booker has his own breakout moment. The campaign has aggressively pursued an “every staffer is an organizer” mentality, he said.

“The candidate has their moment and kind of breaks out, but as a campaign you’d better be ready to capitalize on that,” he said. “And you can really only do that by getting in early, investing in organizing and building upon those relationships.”

First: Thank you. Next: Engagement

At a recent Warren town hall in Dubuque, Iowans were stopped on the sidewalk, at the venue’s entryway and again inside the event space itself by organizers asking them to text their information to the campaign so it could stay in touch.

“We need to thank everybody for coming, and having that data right away makes our follow-up time a lot quicker," Warren’s organizing director, Juliana Amin, said. "But it’s also a mechanism through which organizers will have folks to follow up with, to introduce themselves to on the ground, get to them and start getting them engaged with our campaign.”

The follow-up after an event is the campaign's focus, Amin said.

That’s because Iowa’s Democratic caucuses require a greater commitment from participants than do primaries or general elections that use a simple process and a secret ballot.

Here, Democrats gather in community rooms, school gymnasiums, church basements and even some living rooms for an arcane hourslong process on a cold Iowa winter night. Each Iowan must physically stand for their preferred candidate, in front of their friends and neighbors, to declare their choice.

It’s a lot to ask. And campaign veterans say the best way to get a person’s support — and keep it all the way through caucus night — is to create personal relationships.

“You can’t turn them into a caucusgoer overnight with one conversation,” said Delaney’s state director, Monica Biddix. “It has to be one, two, three conversations and going back to them and following up.”

Caucus organizers get to know local leaders and activists through events, phone calls and face-to-face meetings. But they’re also leveraging data collection, technology and social media to track support at every level.

“The majority of Iowans have not made up their mind yet,” said Harris’ state director, Will Dubbs. “So, we’re also tracking second choices. We’re tracking people who like Kamala and the people who go, ‘Oh yeah, I saw her.’ We’re tracking every tiny little bit of support."

In the caucus process, if a candidate doesn’t garner enough support to meet what’s known as a viability threshold, there’s a realignment period where campaigns compete to claim those displaced caucusgoers.

With such a large field of candidates, "we are very, very honed in on realignment," Dubbs said. “We think that’s a key part of our strategy."

The work between visits

Even as the 2020 Democrats descend on Iowa in seemingly endless droves — already this year candidates have made nearly 300 individual appearances in the state — their staffs are filling those in-between hours with phone calls, meetings and events that can build and sustain momentum while their candidate is away.

Harris has held relatively few public events in Iowa compared to some 2020 contenders — her third trip to the state this week brought her to eight events over five days since announcing.

In her absence, the campaign has created a series of events called Camp Kamala that will be held next week on five Iowa university campuses. The training sessions are focused on giving students information about Harris and the tools to become ambassadors for her on their campuses and in their communities.

The Harris campaign also has deployed its Iowa chair, 2018 secretary of state candidate Deidre DeJear, to hold events of her own. It’s part of creating a series of “warm touches” the campaign hopes will connect with people on a deeper, personal level over things like cold calls and mass text messages.

Warren’s team has built out a series of events, is hosting “office hours” with their organizers in local coffee shops, and has organized house parties to spread their message.

Sanders' team is trying to mobilize its nearly 20,000 volunteers by asking them to host house parties. Sanders' Iowa state director, Misty Rebik, said the campaign is being intentional about its hiring practices.

"We’re being very mindful about who we’re hiring, how we’re hiring, just to make sure we include the most perspectives as possible as we can on the campaign," she said. "And we will have, without a doubt, one of the largest operations in the state out of all the other candidates."