FARGO, N.D. (AP) — North Dakota's Democratic Party expected a big turnout surge for revamped caucuses Tuesday and they got it — so much that the party had to put out an urgent call for volunteers to add staff at its largest site in Fargo.

At midday, voters waited in line outside a union hall in the state's largest and most liberal city for as much as an hour to vote. And traffic was growing as people began coming after work, with cars waiting to turn into the parking lot or searching for a place to park on the street. Five propane heaters were set up to keep people warm in the 31-degree weather, and volunteers served coffee.

For the most part, the mood was light: One man set up a pair of small but powerful speakers on a picnic table and blasted rock music. And one voter who exited the building ran through the crowd holding up his cell phone and yelling, "You're close!'

Rick Gion, a longtime North Dakota Democrat, said he received an "all hands on deck" call from the state party chair shortly before noon on Tuesday, asking for volunteers to help with the Fargo caucus. Gion spent much of his time helping handicapped people, families with babies and other people who may not have dressed for the occasion get moved inside.

“People are so excited about getting President Trump out of office," Gion said. "The lines are long and people are being so patient.”

North Dakota shifted this year from traditional caucuses to so-called “firehouse caucuses” that work much like typical elections, with voters able to show up, cast a ballot and leave. The parties run the process, and Democrats had 14 locations statewide open from 11 a.m. to 7 p.m., with a mail-in option as well. In a spot check elsewhere, turnout was strong in Bismarck and Minot, but without the lines seen in Fargo, where about 250 people were still in line at the scheduled 7 p.m. poll close. It was expected to take about another hour for those voters to finish.

“We’ve seen an exciting number of new voters and many people who need help looking up their voting districts, which adds some time to processing,” party spokesman Alex Rohr said by email. “When we saw long lines, we activated additional volunteers, staff, and equipment. Everyone who is in line when the polls close will have a chance to vote.”

Fourteen pledged delegates were at stake for Bernie Sanders and Joe Biden. With much larger prizes at stake elsewhere, neither candidate had done much in the state. President Donald Trump was unopposed in the GOP's caucuses.

Sanders won North Dakota just four years ago, clobbering Hillary Clinton in the traditional format that rewards highly organized campaigns with fervent followers willing to invest the time necessary to see the process through. The modified process was expected to be friendlier to Biden.

The limited locations and the eight-hour window for voting — less time than a traditional election and with no ability for people to vote before work — meant increased pressure on the caucus sites. Rohr said both were based on the party’s “volunteer force.” He pointed out that the party gave voters a mail-in option for people who didn’t want to or couldn’t travel significant distances to vote, or otherwise had problems.

Democrats were looking for turnout many times higher than the 3,400 people who took part in the 2016 caucuses. Despite the wait, several voters interviewed by The Associated Press said they didn't mind.

Bob Pieri, a professor at North Dakota State University and the last voter in line in Fargo when it was cut off Tuesday evening, said Democrats should be happy at the big turnout.

"They've kind of come out of the woodwork," siad Pieri, who declined to say whom he supports and gave his age only as in his 70s. "In prior elections there has hardly been anyone to populate the voting location.”

Heather Davin, 20, a student at North Dakota State University, parked half a mile away and eventually voted for Sanders, whom she said “has the most gumption in what he is talking about.”

“I am very surprised, very happy to see all these people representing the state," Davin said. "Get your exercise and get your vote.”

Connor Marchus, 20, another Sanders supporter who attends North Dakota State, also liked the revamped caucus format.

“It’s a slight inconvenience but overall when you look at the bigger picture, it’s great to have this many people vote," he said.

Linda Day, 80, of Fargo, voted for Biden.

“He is my man. I guess I’m kind of progressive but I do worry about Bernie being able to beat Trump, and I worry about Bernie having another heart attack," Day said. "The other thing is, I think Trump is very much afraid of Biden.”

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Associated Press writer Doug Glass contributed from Minneapolis.