STOCKHOLM — “Helg seger.”

Those two words, spoken by Rebecka Fallenkvist, a 27-year-old media figure and politician from the Sweden Democrats, the far-right party that took 20 percent in Sweden’s general election last week, sent shivers down spines throughout the country. It’s not the phrase, which is odd and means “weekend victory.” It’s the sound: one letter away from “Hell seger,” the Swedish translation of the Nazi salute “Sieg Heil,” and the war cry of Swedish Nazis for decades.

Ms. Fallenkvist was quick to disavow any Nazi associations. She meant to declare the weekend a victorious one, she said, but the words came out in the wrong order. Perhaps that’s true. But the statement would be entirely in keeping with the party Ms. Fallenkvist represents which, after a steady rise, is now likely to play a major role in the next government.

For Sweden, a country that trades on being a bastion of social democracy, tolerance and fairness, it’s a shock. But perhaps it shouldn’t be. Steadily rising for the past decade, the Swedish far right has profited from the country’s growing inequalities, fostering an obsession with crime and an antipathy to migrants. Its advance marks the end of Swedish exceptionalism, the idea that the country stood out both morally and materially.

There’s no doubt about the party’s Nazi origins. The Sweden Democrats was created in 1988 out of a neo-Nazi group called B.S.S., or Keep Sweden Swedish, and of the party’s 30 founding fathers, 18 had Nazi affiliations, according to a historian and former party member, Tony Gustaffson. Some of the founding fathers had even served in Hitler’s Waffen SS.

Step by step the party changed its image — in 1995 uniforms were forbidden — but the core ideology remained: Immigrants should be persuaded to go home, Swedish culture should be protected and neither Jews nor the Indigenous Sami people were to be considered “real Swedes.” Not even the soccer star Zlatan Ibrahimovic secured the party’s approval, although he was born in the country and is the national team’s record goal scorer. The stances of the current leadership, which has sought to sanitize the party’s reputation, are equally worrying.

Take Linus Bylund, the party’s chief of staff in the Swedish Parliament. In an interview in 2020, he declared that journalists for the national public service radio and television ought to be “punished” if their reporting was biased. Such people, he stated previously, would be “enemies of the nation.” Proximity to power hasn’t softened his views. The day after the recent election, a reporter asked him what he now looked forward to. “Journalist-rugby,” he replied.

Jimmie Akesson, the party’s leader, also surprised a television audience in mid-February when he refused to choose between Joe Biden and Vladimir Putin. It’s of a piece with the party’s accommodating stance on Russia: The Swedish Parliament was so concerned about a journalist who used to work in the party’s office and had contact with Russian intelligence that it denied the journalist accreditation. Add in a cohort of representatives more prosecuted for crimes than any other, organized troll campaigns against opponents and even attempts to undermine faith in the electoral system, and you have the image of a deeply unsavory party.

Even so, the Sweden Democrats’ rise is an impressive right-wing success story. The party entered the Parliament in 2010 with just over 5 percent of the vote — but, under the leadership of Mr. Akesson, it built an efficient, nationwide organization. It more than doubled its share of the vote in 2014 and, after Sweden admitted over 160,000 Syrian refugees, grew even more in the 2018 election. But it’s in this vote that Sweden Democrats secured a sought-after breakthrough with a stunning 20.6 percent of the votes, surpassing the conservative Moderaterna, which had been Sweden’s second-biggest party for over 40 years. Now only the Social Democratic Party, Sweden’s historic party of government, has more support.

This monumental rise is thanks to the dramatic changes in Swedish life over the past three decades. Once one of the most economically equal countries in the world, Sweden has seen the privatization of hospitals, schools and care homes, leading to a notable rise in inequality and a sense of profound loss. The idea of Sweden as a land of equal opportunity, safe from the plagues of extreme left or extreme right, is gone. This obscure collective feeling was waiting for a political response — and the Sweden Democrats have been the most successful in providing it. It was better in the good old days, they say, and people believe them. Back to red cottages and apple trees, to law and order, to women being women and men being men.

For opening this door, the major parties have themselves to blame. Bit by bit, the traditional parties have adopted the point of view and rhetoric on crime and immigrations of the Sweden Democrats Party — but this strategy hasn’t won back any votes. On the contrary, it seems to have helped the far right. In a little more than 12 years, Sweden Democrats has managed to compete with the Social Democrats for working-class voters, with Moderaterna for the support of entrepreneurs and with the Centre Party among the rural population.

The media is culpable, too. In an attempt to protect traditional Swedish democratic values, the mainstream media has often shunned and canceled Sweden Democrats officials and supporters, especially in the party’s early years. But now it seems that this response actually might have had the opposite effect. Individuals leaning toward the Sweden Democrats for various reasons have felt stigmatized: Some haven’t been invited to family gatherings, and in a few cases have even lost their jobs. This has not only fed the party’s self-image as a martyr, but also nurtured even more loyalty among its supporters.

One could argue that the traditional parties have had their part in creating the perfect storm. The Social Democratic party has named the Sweden Democrats their main enemy in the election campaign, making other alternatives almost invisible in the public debate. Us or them, was the strategy. Many, predominantly male Swedes, chose the Sweden Democrats. As for a conservative party like Moderaterna, they have seen their voters abandon them for Sweden Democrats and so Moderaterna reacted by emphasizing the similarities between the two parties until it reached a point where it became hard to distinguish any differences at all.

The result is now plain to see. The Social Democrats, though the largest party, are unable to form a government. Instead, a conservative bloc, led by Ulf Kristersson from Moderaterna, will attempt to take office — as long as it has the support of the Sweden Democrats. Effectively a kingmaker, the party is now one of the most successful far-right parties in Europe since World War II.

It’s a terrifying truth. But we must bear in mind that the majority of the country’s population is not among the Sweden Democrats’ ranks. These people want solutions to real problems — such as a worrying spike in gang and drug-related shootings in several cities — without recourse to ethnic blame games and the vilification of “un-Swedish” culture. As a liberal democrat I will never approve of a party that celebrates its success with references to Hitler’s Nazi ideology, no matter the claim that only by sheer coincidence was the exclamation “Helg Seger” just one letter apart from a Nazi war cry.