A bastion of welfare and equality, Sweden faces an election on Sunday that could be its most tumultuous in a century. As in other democracies across the world, the establishment is being challenged on multiple fronts. The long-dominant Social Democrats are headed for their worst result since general voting started in 1921. The biggest opposition party, the conservative Moderates, may see its backing cut to about half the electoral support it enjoyed at the start of this decade.

For a country that prides itself on stability and is seen as a model for social democracy across the world, the development is hard to grasp. But voters are now flocking to a party that was born of Sweden's neo-Nazi, white supremacist movement.

The Sweden Democrats, whose stated goal is to rip their country out of the European Union, could win about 20 percent of the vote on Sept. 9. Fifteen years ago they weren't even big enough to make it into the parliament. Meanwhile, the other end of the political spectrum is also poised to do well, with the former communist Left Party set to win almost 10 percent.