CLEAR LAKE, Ia. — The Democrats running for president have consistently argued that Donald Trump’s election has brought America to a critical juncture that demands action.

But their calls to defeat him and unify the country took on greater weight Friday following a week in which racism and gun violence have driven the national conversation after multiple mass shootings.

Twenty-one Democratic presidential candidates converged on the historic Surf Ballroom in Clear Lake, Iowa, on Friday night for the annual Democratic Wing Ding fundraiser where they each were given five minutes to make their cases to hundreds of northwest Iowa Democrats.

U.S. Sen. Cory Booker of New Jersey prefaced his speech by saying he would use it a little differently than he might otherwise, opting to call for a moral awakening of the American people rather than promote a policy agenda.

“This is not a referendum on one guy in one office,” he said. “This is a referendum on us and who are we going to be to each other. This is one of those moral moments in our nation that’s going to define the character of our country. And this is a week where I will not let the slaughter of our fellow citizens just disappear within the next media cycle.”

Booker likened the moment to the bombing of a black church in Birmingham, Alabama, that killed four black girls but propelled the civil rights movement forward and to the Shirtwaist Factory Fire that killed dozens but ultimately led to greater workplace protections.

“This has to be that moment in America,” he said.

Booker, Buttigieg get the crowds on their feet

Booker started quietly but ended his speech with a fiery call for the “United States of America to rise again” that brought the crowd to its feet.

South Bend, Indiana, Mayor Pete Buttigieg had the crowd’s attention from the start, walking onstage amid raucous cheers.

He, too, emphasized the weight of this moment in history.

“We’re living in a moment that’s even more serious than what the Trump presidency represents,” he said. “Because you’ve got to ask yourself: How does a guy like Donald Trump ever get within cheating distance of the Oval Office to begin with? That doesn’t happen in ordinary times. It happens if we’re already in crisis, and we have seen it.”

Former Vice President Joe Biden, who has centered his entire candidacy on calling out the president, repeated many of the same points he makes consistently on the campaign trail.

“Ladies and gentlemen, it’s up to all of us — 330 million Americans — who have to do what our president can’t,” he said. “Standing together, stand against hate, stand up to — let’s call this what it is — this is white nationalism. This is white supremacy. It’s not only our values that are under assault. Everything that makes America America is under assault.”

Beto O’Rourke, the former U.S. Rep. from Texas and an El Paso native, canceled his plans to attend the dinner, opting instead to stay with his community after a gunman posted a racist manifesto and opened fire in a Walmart there. His campaign organized a moment of silence that brought all of the presidential campaigns together before the dinner began, and O’Rourke addressed the crowd in a recorded video message instead.

U.S. Rep. Tim Ryan of Ohio also drew big applause by pledging to fight for gun control measures.

“People are dying on the streets of this country, getting killed by weapons made for battlefields not neighborhoods in places like Dayton, Ohio," he said.

Paula Schwabe, a 56-year-old nurse from Aplington who attended the Wing Ding, said she appreciated that the candidates discussed the recent mass shootings.

“Even in the middle of all this, electing a president, we can't forget what's happening in the world, just down the block, basically,” she said.

Supporters fired up

Frank Rottinghaus, a 68-year-old from Charles City, said he likes U.S. Sen. Kamala Harris of California, but "Booker took a different approach — he fired people up and gave them a mission."

Though many of the night’s speeches took on a somber tone, the mood outside of the Surf Ballroom prior to the event’s start was boisterous and festive.

Many of the campaigns had gathered their supporters to hold signs and chant in a display of support and enthusiasm as attendees filed into the building.

Buttigieg's team danced to Earth Wind and Fire’s “September,” Harris’ supporters stood out in bright yellow as they chanted and yelled, and entrepreneur Andrew Yang’s fans held signs that said simply, “Math.”

U.S. Sen. Elizabeth Warren’s team lined the side of the street chanting and dancing for hours before the event began. And although they already outnumbered the other campaigns, even more of the Massachusetts senator's supporters arrived late in the afternoon to march with Warren's branded Winnebago as it pulled up to the mayhem. Warren was given a rock star’s welcome when she stepped out of the RV, hugging her volunteers and posing for pictures.

Buttigieg, Booker, Harris and U.S. Sen. Kirsten Gillibrand of New York all stopped to greet their supporters outside the venue before making their way inside.

Also in attendance: U.S. Sen. Michael Bennet of Colorado, Montana Gov. Steve Bullock, former U.S. housing secretary Julian Castro, New York City Mayor Bill de Blasio, former U.S. Rep. John Delaney of Maryland, U.S. Rep. Tulsi Gabbard of Hawaii, former Colorado Gov. John Hickenlooper, Washington Gov. Jay Inslee, U.S. Sen. Amy Klobuchar of Minnesota, U.S. Sen. Bernie Sanders of New York, retired U.S. Navy officer Joe Sestak, activist Tom Steyer and spiritual leader Marianne Williamson.

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Des Moines Register reporters Nick Coltrain and Gage Miskimen contributed to this report.