But these politics also attract a significant fringe element. Dozens of bikers motor onto the site, some whose opinions are as extreme as their tattoos.

"My biker club is very right-wing," said Martin, 44, who works in security on an offshore oil rig. "We are hoping for some fun today: some beer and a good speech from Jimmie, our upcoming prime minister."

Why does he support the Sweden Democrats? "I think that's pretty obvious," Martin said, who also declined to give his full name. "They will stop the Muslim invasion. The whole of Islam is wrong. I'm pro-Swedish."

A few feet away was Marina Coffa, 50, a school worker wearing a leather jacket with a "Lady Biker" patch. "The politicians are so naive because they tell us we're not allowed to say we love Sweden," she said.

Nachos and knyppling

With his neat stubble, trendy glasses and light-blue blazer, Åkesson is the face of a party trying to clean up its image. One of its founding members in 1988 was a veteran of the Nazi SS. Its rallies in the 1990s were dominated by skinhead thugs.

Åkesson's tenure since 2005 has seen a litany of representatives ousted for making racist statements. The party declined NBC News' requests to interview him.

"Yeah, we have an image problem and we are constantly working on that," said Karlsson, who earlier this year was accused of using language with anti-Semitic overtones when defending a colleague who suggested Jews and the country’s ethnic Sami people were not true Swedes.

Karlsson was also pilloried in 2010 after he said Los Angeles Galaxy soccer star Zlatan Ibrahimovic, perhaps the most famous Swede on the planet, didn't have Swedish "body language."

Zlatan Ibrahimovic. Katharine Lotze / Getty Images

Ibrahimovic was born in Sweden, the son of a Muslim who relocated from Yugoslavia.

Asked whether Ibrahimovic is Swedish, lawmaker Jomshof told NBC News, "I don't answer this question."

Jomshof's parents emigrated from Finland in the 1960s, but he insists he's no hypocrite. Today's immigrants are different, he claimed, because "they are telling us how to live our lives."

Tobias Andersson agrees. At 22, the leader of the party's youth wing will likely become a lawmaker next month. Andersson joined the Sweden Democrats at 16, attracted by its tough stance on criminal justice.

But he becomes most animated when discussing immigration, which he said is "bad in every way possible."

Immigration aside, the party wants to limit abortion and increase defense spending. It opposes Sweden's membership in the European Union and has expressed skepticism about man-made climate change.

Jimmie Åkesson plays keyboards at the festival. His band is called Bedårande barn — or "Adorable Children" in English. Julia Lindemalm / for NBC News

Even sympathetic voices accept that Sweden was unprepared for the immigrant incomers of 2015. Tightened borders slowed that to a trickle. Now the debate centers around integration.

The Sweden Democrats promoted their vision of national culture by hosting traditional activities including lessons in schottis, a 19th-century dance.

"It's taken us perhaps 1,000 years to become what we are today," Jomshof said.

This viewpoint has been criticized by Swedish anthropologists, who say culture is never a constant and has always evolved throughout history. The festival raised other questions.

On one table, an artist from Stockholm named Maud Hemberg was teaching people a type of medieval lace-making called knyppling. But she seemed uncertain when asked about its historical significance, and why the Sweden Democrats are so determined to preserve skills like it.

"I think it's from Germany," said Hemberg, 52, who wore a traditional dress. "It's quite old but I'm not sure. I haven't actually looked into it."

Ilvars Hansson. Julia Lindemalm / for NBC News

With his blue baseball cap reading "Make Sweden Great Again," Ilvars Hansson, 72, added that "everything has gone bananas" because of immigration. Hansson is an immigrant who arrived from Germany in 1951.

Elsewhere, the main food stall at this celebration of Swedishness was a Mexican-themed nachos stand.

'Don't forget to try the falafel'

Police say there is scant evidence that immigration alone leads to crime.

Jomshof floated a familiar Sweden Democrat theory that before immigration "we have never had problems with gang rapes" and "men from the Middle East raping Swedish women."

The number of reported sexual assaults has increased in recent years, but authorities attribute the rise to victims being increasingly willing to come forward.

What the Sweden Democrats have focused on are the "no-go areas," such as Rosengård, a suburb of Malmö featuring imposing house blocks but also tree-lined cycle routes and pedestrian walkways. Around 80 percent of Rosengård residents either were born abroad or are the second generation of their family in Sweden.

"To be honest I actually laugh when I read the news reports," Malmö police spokesman Nils Norling said. "It's one of the most quiet, boring areas you can find. It's like any city. It's a place where people live."

His advice before visiting? "Don't forget to try the falafel — it's great!"

The Rosengård suburb of Malmö, Sweden. Julia Lindemalm / for NBC News

"It's a very nice area," added Fatma Elzein, 52, who left Lebanon in the 1980s and now works at a women's collective dedicated to helping female immigrants find work. "We live together, we support each other and everyone is like a family."

But there has been a failure to integrate some newcomers. Around half of the people NBC News tried to interview during a visit to Rosengård last week could not speak Swedish.

Riots in Rosengård a decade ago linger in memory — "it was a small war," police Superintendent Glen Sjögren recalled — and just this week, gangs were blamed for setting 80 cars on fire in similar neighborhoods across Sweden.

Analysts say this refocused the election debate on immigration and helped the Sweden Democrats.

But even if they win most seats next month, they may not gain power. Governments here rule by coalition; the other parties have suggested that they would not ally with their far-right colleagues.

Nevertheless, like supporters of Trump and Britain's Brexit before them, many Swedish populists see this as their moment.

"It's the election of our destiny, if that's the right word?" said Penila Johansson, 46, a forklift truck driver from Gothenburg at the festival. "Yes, it's going to decide our destiny."

CORRECTION (Aug. 17, 2018, 10 a.m. ET): A previous version of a caption with this article misspelled the first name of a festivalgoer in a blue "Make Sweden Great Again" cap. He is Ilvars Hansson, not Ivars.

CORRECTION (Aug. 17, 2018, 12:05 p.m. ET): A previous version of this article misstated a potential result of the Sept. 9 election. If the Sweden Democrats win as much as 25 percent of the vote, as polls indicate, they would likely earn more seats in Parliament than any other single party, not a majority of seats.