SIOUX CITY, Iowa — Julián Castro had shaken every hand in an Iowa lawyer’s living room and patiently waited to deliver his presidential stump speech to the 57 Democrats who had turned out to hear it. But the people in the dining room nibbling on pita chips hadn’t gotten the message — and didn’t tune in to the former San Antonio mayor until a man standing near the front put two fingers into his mouth and blew a loud, shrill whistle to silence the room.

A day later and 200 miles across the state in Ankeny, Sen. Kamala D. Harris (D-Calif.) marched onstage to a standing ovation and looked out on a room still filling with voters. Her first public Iowa campaign event drew 760 people and left staffers scrambling to add extra seats.

Half a dozen prominent Democrats descended on Iowa this weekend, seeking momentum for a primary presidential campaign or testing whether to plunge into an already crowded field. This weekend, Iowa forked into two campaigns.

On one side was Harris, who continues to draw the large, selfie-seeking crowds she has enjoyed since announcing her bid. On the other side was everyone else, Democrats like Castro, former Colorado Gov. John Hickenlooper, Rep. Tulsi Gabbard of Hawaii and New York Mayor Bill de Blasio, whose crowds numbered in the double digits and who mostly dubbed themselves underdogs as they implored Iowans to keep an open mind.

“When I ran for [Denver] mayor, no one thought I had a chance,” said Hickenlooper, who is exploring whether to enter the race and spoke over the sounds of the espresso machine and an uncooperative sound system at a coffeehouse in Sioux City. “When I ran for governor, no one thought I had a chance. Now, no one thinks I have a chance.”

The point of his joke was underscored a few minutes later during an impromptu news conference with reporters. The first question he was asked was how to say and spell his name. Then he was asked his title.

“Free agent. Until about six weeks ago, I was the governor of Colorado,” he said.

About 45 minutes before Sen. Michael F. Bennet of Colorado was supposed to address the Polk County Democrats on Friday afternoon, Deb Hansen hurried to the door of Doc’s Lounge, a small bar nestled in a Johnston, Iowa, strip mall, lugging a portable speaker. Organizers had thought they could use the equipment from a local band for the senator’s remarks, but the band wasn’t due until later, so Hansen and her 6-year-old granddaughter came to the rescue. Kenna Meredith snacked at a high-top table while her grandmother bustled around to help. Volunteers hung a sign welcoming Bennet, another potential presidential candidate, as a few voters trickled in and grabbed a beer.

“You should complain to the Polk County Democrats,” a voter joked to Bennet’s staff, comparing his welcome to that of the Democratic senator from Minnesota. “Amy Klobuchar’s sign was twice that size.”

About 45 minutes before Harris was scheduled to address the Asian and Latino Coalition at the Iowa State Capitol on Saturday — what was supposed to be a smaller, private event before her town hall — national and local news cameras were set up in the back of the room. Chairs around a grand table were labeled with names of participants, each with a microphone nearby, and staffers worried whether the room, intended for 60 onlookers, would hold the more than 100 or so who had RSVP’ed.

When she answered a question about U.S. failures in Puerto Rico after Hurricane Maria with the words “as president, because I intend to win this election,” the room cheered.

“She is already trying to bring people together,” said Prakash Kopparapu, chairman of the coalition.

At the town hall, Harris seemed to imply a heightened status as she spoke of “leadership qualities,” “a vision for America” and a “track record of public service” that voters should consider.

“I have served as a leader in local government, state government and now the federal government. I have seen how government impacts the lives of people at each level, and the experience I’ve had — including running an office of almost 5,000 people when I was attorney general of California — tells me the importance of thinking when we have these powerful positions about how our work impacts real human beings and prioritizing that.”

To be sure, other Democratic presidential candidates who have raised millions of dollars and have brought in large crowds were not in Iowa this weekend. Sen. Cory Booker of New Jersey campaigned in Nevada on Sunday, while Sen. Elizabeth Warren of Massachusetts spent the weekend in New Hampshire. Sen. Bernie Sanders (I-Vt.), who announced his candidacy Tuesday, will start his campaign events next weekend.

Still, the sense of candidate haves and have-nots was apparent across the state — and occasionally across the room.

At one point, Harris, Castro and Hickenlooper were at the same event, a Saturday night soup dinner in Ames. Castro entered quietly from the back and dutifully went up to tables, shook hands and introduced himself. When people noticed Harris had arrived, attendees and TV cameras gravitated toward her, blocking the room’s central aisle.

Candidates and voters were hesitant to draw meaning from the duality of one weekend in Iowa nearly a year out from the caucuses that will kick off 2020 voting. The field of candidates already is larger than most caucus veterans can recall. And voters said they had never received this much attention from candidates so early in an election cycle.

Iowans who attended the events said they were dizzy but also delighted, hoping to fulfill Iowa’s traditional role of thinning the field.

“Iowans see it as, you know, ‘this is our job in American democracy,’ ” said Al Sturgeon, a Sioux City lawyer and a member of the Truman Club, which hosts Democratic presidential candidates, including Castro on Friday.

Almost all of the candidates who campaigned in Sioux City had been mayors or governors — executives who touted bipartisan success in solving problems, not just debating them.

“We need people who have visions,” Hickenlooper told reporters after spelling his name. “Many of the senators out there, they’re dreamers, good at debating back and forth. I’m a doer.”

De Blasio, who said he has not decided whether to run, told voters in Sioux City that Democrats need to nominate an “unapologetic progressive” who could excite the party’s voters and provide a clear contrast to President Trump.

But few voters seemed to have picked a candidate in a field of Democrats with similar positions on issues like health care, criminal justice and climate change.

“A lot of the people running as Democrats have the same or similar messages,” said Tim Bottaro, a personal injury attorney who leads the Truman Club. “So in a lot of ways, it’s about who is the best messenger.”

That might give an advantage to someone like Castro if the party thinks the best contrast to Trump is “someone who is young and fresh-faced,” Bottaro said.

But the Iowan said he has talked to only a few candidates face to face and is far from done evaluating the field. He expects the next year to be much like this weekend, full of stump speeches and handshakes from people trying to build steam.

It was unclear whether Castro had succeeded in doing that after his speech at Sturgeon’s house.

Of the nearly 60 Democrats who showed up, only a handful wrote down their contact information so they could receive mailings from Castro’s campaign. Most didn’t grab a free bumper sticker on the way out.

The pita chips devoured, Sturgeon and Bottaro were already looking beyond Castro. There were still more candidates to invite to town, including, perhaps, the senator from Ohio.

“Are you still okay with hosting Sherrod Brown?” Bottaro asked.