Sweden was thrown into political turmoil on Sunday when the rightwing, populist Sweden Democrats gained 12.9 per cent of the vote, becoming the country’s third largest party.

Support for the Sweden Democrats, led by Jimmie Åkesson nearly doubled compared to the previous election in 2010, when it got 7.2 per cent.

Sweden will now see a shift in power, from a centre-right coalition government to a centre-left government led by the Social Democrats. While Social Democrat leader Stefan Löfven has vowed not to cooperate with the Sweden Democrats, there is a strong chance that they will become kingmakers in parliament. The Sweden Democrats also made advances in local elections and could come to hold sway in half of the country’s municipalities.

While the party has instituted a zero-tolerance policy on racism, a number of candidates were forced to resign after making racist comments online. A 20-year-old candidate quit days before the election after photos emerged of her wearing a swastika.

The party supports Sweden’s ban on ritual slaughter and wants to criminalise non-medical circumcision. It has its roots in the racist “Keep Sweden Swedish”movement, which co-operatedwith Nazi and fascist groups in the 1980s.

Social Democrats cheered as their leader, Stefan Löfven, held his victory speech Sunday, but he will form a government based on one of the party’s worst election results ever.

Stepping on to stage at the Social Democrats’ election HQ, Stefan Löfven thanked his party colleagues for their hard work and promised to form a government that will invest in jobs, schools and welfare.

“The Swedish people demanded change and they will see change,” Löfven said, vowing to focus on solidarity, feminism and anti-racism.

However, Löfven faces a tough task. With just over 31 percent support for his party, he is having to form a government based on one of the worst election results for the Social Democrats in a century. And while Löfven has said his main priority is to ensure the Sweden Democrats don’t get any influence, the far-right party is now the third largest in Parliament.

Amidst the celebrations at the Social Democrats’ election party, there was also concern and disappointment.

Darina Agha, the international secretary of the Social Democrat youth wing SSU, said she has mixed feelings about the election outcome.

“I’m of course very glad that we can change government and that Stefan Löfven will finally be the prime minister of Sweden, but I’m also concerned about the Sweden Democrats of course,” Agha told Radio Sweden, adding: “I’m concerned that their support is so strong – at 13 percent – and I’m concerned about how we will form a government and what involvement the Sweden Democrats will have to have.”

Others kept up a more positive spirit as Löfven stepped off the stage after his speech and a disco kicked off. Roger Siren, an employee at the Social Democrat party headquarters, said:

“He has offered an outstretched hand to anybody who wants to work for the best for Sweden, with the outcome of the election as a background, of course so it was all I had hoped for. This is a chance for Sweden to start anew and with the Social Democrats in the lead and hopefully a broad cooperation of all parties that want to work for the best for Sweden. That’s what the election result means.”

What that broad cooperation will look like remains to be seen, as Jan Larsson chief campaign manager for the Social Democrats, told Radio Sweden.

“Stefan is a cooperation-oriented politician and what the situation right now in Sweden demands in more cooperation and less bloc politics so I hope we will be able to open new lines of cooperation, also between the Left and the Right,” Larsson said.

Regarding how to deal with the Sweden Democrats, Larsson said their high result is a signal to the “more democratically-oriented parties” that Sweden Democrat supporters’ concerns must be taken

“People are worried about unemployment, the needs of the elderly and so on so we need to hear those signals that people are sending us, “Larsson said, adding:

“When it comes to the Parliament, it means that the democratically-oriented parties must take responsibility for not giving influence to this party. That goes not just for the Parliament level, but also on the local and regional levels. We need to cooperate more in order to isolate this party. We need to find democratic lines of cooperation in order to get around them. So I hope that means that some of the centre-right parties will be more open to cooperation going forward.”

Richard Milne, Nordic and Baltic correspondent for the Financial Times, tells Radio Sweden that messy negotiations could confound international perceptions of Sweden as a stable nation.

Radio Sweden caught up with Milne at the Social Democrat Party’s election HQ Sunday night, where he was covering the election for the FT.

Milne said that, for an international readership, there are two major points of interest when it comes to Sweden’s general election, one being the change of government, with the centre-left beating the centre-right. The real sensation, however, is the score of the anti-immigrant Sweden Democrats, he said.

“Thirteen percent – that’s a figure that nobody predicted,” Milne said. “It puts in Sweden in line with some other European countries and it puts the Sweden Democrats in a powerful position as disrupters, if not kingmakers.”

What distinguishes the Sweden Democrats from corresponding parties in the Nordic countries, Milne said, is that they have their roots in the neo-Nazi movement and that is not true for the other “populist, right-wing, anti-immigrant parties” in the countries that neighbour Sweden.

However, the government shift is not necessarily dramatic in itself, Milne said. From a global perspective, the difference between the centre-right and the centre-left in Sweden is pretty minute, he pointed out.

“Not that much changes now, but the international community looked at the outgoing government as a very reforming, very interesting centre-right government… What could confound international perceptions a bit is if there are really messy negotiations to form a government.”

“Sweden has very much been an oasis of stability after the financial crisis so that could represent some political risk,” Milne said.