CLEAR LAKE, Iowa — The Democratic presidential candidates paused here for a moment of silence for the victims of the mass shootings in El Paso and Dayton, Ohio, underscoring how the turbulent events of the past week have refocused the primary contest.
The brief lull in the primary campaign came as nearly the entire field descended on Northern Iowa Friday night after traversing the state for a series of cattle calls, town hall meetings and to sample the pork-laden delicacies on offer at the Iowa State Fair in Des Moines.
In speech after speech at the annual Wing Ding dinner, the Democratic field assailed President Trump and Republicans for their lack of action on gun control, painting the party as allied with white supremacy.
“There are not two sides when the other side is the Ku Klux Klan,” Senator Amy Klobuchar of Minnesota told 1,600 activists and voters gathered for the Wing Ding dinner. “There is only one side and that is the American side.”
Mayor Pete Buttigieg of South Bend, Ind., who received rapturous applause from the crowd, focused his remarks on turning the page from the Trump presidency, describing white nationalism as a “national security threat.”
“We’ve got to win not just the era but the future of this country,” Mr. Buttigieg said. “We are going to fix things in this country, we are going to do it together.”
The annual event, held at Clear Lake’s iconic Surf Ballroom, where Buddy Holly played his final rock show before dying in a plane crash in a nearby cornfield, has become an essential stop for Democratic presidential contenders.
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Barack Obama spoke here in 2007 before his presidential campaign caught fire. And last year, when Michael Avenatti, the celebrity attorney, was weighing a presidential bid, he wowed the crowd and presaged the 2020 campaign by urging Democrats to fight as dirty as Mr. Trump does.
(Mr. Avenatti abandoned his presidential hopes in December. Four months later he was charged in a scheme to extort Nike, the shoe manufacturer.)
Since the mass shootings last weekend, many in the Democratic primary field have heightened their denunciations of Mr. Trump, labeling him a racist and a white supremacist. The back-to-back shootings shook the nation giving Democratic candidates fresh opportunities to contrast themselves with the man they hope to replace next year.
“I think its further harming the soul of our nation, and I think a lot of folks are feeling that,” Senator Cory Booker of New Jersey said in an interview in the parking lot outside the event.
As he left the White House for a vacation at his golf club in New Jersey on Friday night, Mr. Trump called for lawmakers to come together and pass “meaningful” background checks, a sign that the president finds himself under new political pressure.
Even so, there were no major signals on Friday from the National Rifle Association, the White House or Capitol Hill that action on the politically fraught issue was closer to compromise or resolution.
Gov. Steve Bullock of Montana questioned that the president would take action, pointing to the success of the N.R.A. in convincing Mr. Trump to abandon certain gun control efforts in the past.
“This is bigger than the N.R.A.,” said Mr. Bullock, in an interview before the dinner. “As a gun owner, I think gun owners are saying it’s time to get some common sense into this.”
Former Representative Beto O’Rourke skipped the event, canceling his Iowa schedule to attend memorials and visit with shooting victims in El Paso, his mourning hometown.
The speeches at the Wing Ding dinner surpassed the three-hour mark, with 22 candidates each delivering their pitch in back-to-back-to-back five-minute increments to a sweaty room of Democratic activists. Several opened their comments with cracks about the size of the field, a reality that’s begun to worry party officials and voters who fear the crowded race forces candidates to undermine each other to seek attention.
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Outside, young boosters for a half-dozen campaigns chanted and screamed at each other. Someone played “come on Eileen” for no discernible reason. And former Vice President Joseph R. Biden Jr. slow jogged outside to greet his supporters.
Of course, as Mr. Holly once crooned, everyday the caucuses are “a-getting closer” and the race is “a-getting faster.” The weekend signifies the unofficial start of the fall campaign season, a time when the field is likely to narrow as candidates fail to qualify for debates and start hemorrhaging campaign cash.
The dinner comes as the field battles to overtake Mr. Biden who’s commanded a steady lead in the race despite a series of gaffes. On Thursday evening, Mr. Biden raised eyebrows during a speech in Iowa when he said that “poor kids are just as bright and just as talented as white kids.”
A new survey in the state shows Senator Elizabeth Warren of Massachusetts gaining ground and Senator Bernie Sanders sliding. The Vermont senator’s win in the caucuses three years ago fueled his insurgent campaign.
Both senators will greet voters at the fair this weekend, joining a parade of candidates stopping by the beloved annual event that draws voters from across the state.
Julián Castro took his children on a tour of the cattle barns that included the former Housing secretary taking an unfortunate step in cow manure. Representative Tulsi Gabbard sampled the vegan corn dog, hoping she did not offend Iowans by skipping the famous pork chop-on-a-stick.
Andrew Yang, a tech entrepreneur who qualified on Thursday for the next debate, regaled voters and reporters with his experience eating supersized turkey legs, as he stopped for photos during a tour of the fair.
“I’m a big fan of Renaissance fairs,” he explained.
Taffy Brodesser-Akner contributed reporting from Clear Lake.