However, both of the main parties have previously said that they will not form a coalition with Akesson's faction, meaning that a minority government, grand coalition or prolonged political crisis are all on the table.
Roth said "this election result is unfortunately a turning point for Sweden and Europe". And rather than countering the Sweden Democrats' anti-Muslim, anti-immigrant rhetoric with a vision of their own, the liberals shifted to the right with proposals that included sending the army into neighborhoods with high crime rates.
The far-right wants to curb immigration and has called for Sweden to leave the EU.
Yesterday's Communist Party of Sweden is now known as the Left Party-a perfectly respectable party that campaigned in alliance with the Social Democrats.
Like its far-right counterparts across Europe, the Sweden Democrats party has taken pains to move into the mainstream and, to a certain extent, tone down its rhetoric in order to appeal to a broader swath of the electorate.
If the Sweden Democrats win a quarter of the vote, it would be a sensation in a country described as a "humanitarian superpower" in 2014 by the prime minister of the time, the Moderate party's Fredrik Reinfeldt.
"Now we will gain influence in Swedish politics for real", Sweden Democrat Jimmie Akesson told a cheering crowd of supporters as the results came in. Speculation about viable options includes a combination of the Social Democrats, the Centre Party and Liberal Party, with parliamentary support from the Greens and the Left Party.
Both sides laid claim to being best placed to form a government, although votes from Swedes living overseas are not due to be declared until Wednesday and these could still sway the final outcome slightly. Although they won less support than expected, it is still enough to create deadlock: The existing center-left and center-right coalitions, both of which have ruled out explicit collaboration with the Sweden Democrats, are neck and neck, but neither is nowhere near having the seats necessary for a majority.
Swedish Prime Minister Stefan Lofven of the Social Democratic Party talks to media in Stockholm, on September 9, 2018.
Lofven has made clear he won't work with the Sweden Democrats and is urging cooperation across other parties to block the nationalist group's influence. Meanwhile, next-door in Finland, the populist True Finns party was included in the center-right government in 2016.
The Sweden Democrats, a party with roots in the white supremacist fringe, had 17.6 percent, up from 12.9 percent in the last election four years ago.
Sweden's Social Democrats have been the largest party in the Riksdag for more than 100 years.
"It's not that they are shy voters, but that they are distrustful of the polling agencies", said Henrik Ekengren Oscarsson, a professor in political science at Gothenburg University. Some critics say that these situations also compel mainstream parties to pander toward the fringes - a criticism that certainly has emerged about Rutte. The only possible way to form a successful governing coalition, therefore, would be for the parties to secure support from their ideological opponents.
"Terrible! I just wanna cry when I think about it", said Veronica Lundqvist, referring to the Sweden Democrats after she left a voting booth in central Stockholm.
But it's also interesting to note that immigration may not have turned out to be quite such an important factor to voters than expected.
Marine Le Pen, leader of France's far-right euroskeptic National Rally, said on Twitter: "Another bad night for the European Union in perspective". That raised questions whether the parties might find a way for the far-right party to vote with the Moderates at least part of the time and helping to install a center-right leader in the prime minister's office.