CEDAR RAPIDS, Iowa (Reuters) - The final countdown to the Iowa caucuses is on.

Ahead of Monday night’s caucuses, which kick off the state-by-state nominating process to pick U.S. presidential nominees, Democratic candidates made their closing pitches in earnest.

Get the latest from the Iowa caucuses: here

Public opinion polls show a close race among the top of the 11 Democratic contenders vying to challenge Republican President Donald Trump in November. U.S. Senator Bernie Sanders and former Vice President Joe Biden are neck-in-neck for first place, with U.S. Senator Elizabeth Warren and Pete Buttigieg, the former mayor of South Bend, Indiana, not far behind.

“I would call it the Super Bowl of campaigns,” U.S. Senator Amy Klobuchar, whose long-shot bid has strengthened in recent weeks, quipped in a nod to the American football championship taking place on Sunday.

Here is what is happening in Iowa on the campaign trail:

‘BERN-CHELLA’

A confident Sanders, riding high in the polls in Iowa, drew a crowd of 3,000 people Saturday night at a star-studded event at Cedar Rapids’ U.S. Cellular Center.

The band Vampire Weekend was arguably the true headliner for the mostly young attendees who make up the 78-year-old’s enthusiastic base. Along with a gig Friday night in Clive that featured the folk musician Bon Iver, the weekend rally was dubbed “Bern-chella,” after the Coachella music festival.

Sanders’ warm-up acts included activist and academic Cornel West, filmmaker Michael Moore and a raft of progressive politicians.

“The reason we’re going to win here in Iowa, the reason we’re going to win the Democratic nomination, is because we are a campaign of us, not me,” Sanders said.

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The campaign said the crowd was the biggest yet for any Democratic candidate this election cycle and ushered in a weekend of high turnout as voters sought a last glimpse of candidates before the caucuses.

But Tyler Martell, 28, a teacher from Wisconsin who was in Iowa to see several candidates even though he cannot participate in the caucus, said Sanders’ brand of democratic socialism would be a tough sell in a general election against Trump, who drew an estimated 6,000 people to the same venue in 2017, after taking office.

“I think he would be the least electable out of all them,” Martell said. “I’m not saying Bernie can’t win, but if Democrats want a sure thing, they should go with somebody else.”

CONFUSING CAUCUSES

The two-step Iowa caucuses can be confusing even for Americans who follow politics closely. This year they attracted a group of European lawmakers and legislative staffers who attended campaign events to better understand the U.S. electoral system.

The caucuses require voters to attend a meeting and vote in the open by raising their hands or gathering with fellow supporters. After the initial tally in each location, supporters of any candidate who fails to register 15% of the vote may “realign” with another contender, before a final count is conducted to determine the winner.

Kerstin Lundgren, a longtime Swedish Parliament member who was waiting to see Warren in Indianola, said she was impressed by how engaged Iowans – and the volunteers pouring into the state from all around the United States – are in the political process.

Other international interest came from a group of about 20 students from Australia who attended a rally for Sanders in Indianola on Saturday.

SUPER BOWL WATCH PARTIES

Some of the candidates capped their super-charged schedules on Sunday by joining Iowans to watch the Super Bowl.

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“I’m asking you take this over the goal line for me,” Klobuchar said, half-joking at her own football metaphors at a watch party in Johnston. “I want you to score a touch down. ...OK, that’s enough,” she added, to cheers and laughter.

Sanders’ campaign hosted a “big game watch party” in Des Moines, while Warren dropped by a party hosted by a liberal activist group in the same city.

Buttigieg’s campaign said he planned to visit a few Des Moines-area bars during the game.

Former New York Mayor Michael Bloomberg is skipping Iowa as part of his unorthodox bid, but he showed up at Super Bowl parties across the United States in a multi-million-dollar commercial for his campaign that ran during the game.

Trump’s campaign also ran a Super Bowl ad.

The three U.S. senators might not be able to stick around for the final score. They are due back in Washington by late morning on Monday, when closing arguments begin in Trump’s impeachment trial in the Senate. Warren has said she will go back Sunday night.

LAST LOOK

Dozens of schoolchildren packed “selfie lines” to take pictures with Warren, crowds overflowed high school gymnasiums to see Klobuchar, and hundreds waited in line outside a Biden rally in Des Moines as thousands of voters and activists turned out for a last look at the candidates.

An event planned as a canvass launch by Sanders in Cedar Rapids on Sunday drew such a large crowd of volunteers that it was hastily turned into a rally in the parking lot.

In Indianola, 1,100 people showed up for a rally featuring Warren in a space meant to hold just 350, prompting the senator to address the overflow crowd in the lobby before heading inside.

Warren drew about 500 people to Iowa State University in Ames on Sunday, where a line of children waited to have their pictures taken with her. Warren crouched down to talk to 6-year-old Maddie O’Donnell and her mom, Jamie. Warren asked Maddie to “help in this fight,” securing a “pinky promise” by intertwining their pinky fingers.

More than 2,000 people crowded Buttigieg’s last major rally before the caucus at Lincoln High School in Des Moines. Asked what he thought about voters who are “tired of the president but don’t think a Democrat can win,” Buttigieg responded with a nod to Iowa’s influential nominating process and the round of elections and caucuses that kick off on Monday.

“I can give my answer,” Buttigieg said. “But starting tomorrow you can give your answer.”