When acting Sweden Democrat (SD; Sverigedemokraterna) leader Mattias Karlsson recently said that Islamism is "a greater threat than Nazism," he faced criticism from both Muslims and Jews. But Karlsson's views, and those of the party he represents, have been gaining support throughout Scandinavia since the end of the Cold War.

Almost immediately after the wall fell, the SD were on the rise. In the 1991 federal election, they received 0.1% of the popular vote for the parliament (Riksdag). By 1994 it had tripled to 0.3%, increasing to 1.4% in 2002, 2.9% in 2006, 5.7% in 2010, and 13% in 2014. During each election, the SD's share of the popular vote has -- on average -- doubled. Over this time, the international migrant stock proportion in Sweden increased by more than 50 percent, currently standing at 14 percent of the total population.

Some of the supposedly "extreme right" policies of the SD include an opposition to multiculturalism, instead favoring integration and assimilation within a multi-ethnic framework, they support the repatriation of foreign citizens found guilty of serious crimes, reject many components of the European Union, and promote the traditional nuclear family. Hardly "extreme" by any reasonable definition. In fact, mainstream would be a more apt characterization.

Next door in Norway, the Progress Party (Fremskrittspartiet) started its electoral rise in the late 1980s -- moving up from 2% to 5% in the parliamentary elections between 1973 and 1985 up to 13% in 1989. After a poor election performance in 1993, the party rose to over 15% in 1997, maintained this level through the 2001 elections, then reached 22% in 2005, 23% in 2009, and dropped to 16% in 2013.

In recent weeks, the Fremskrittspartiet has threatened that the current ruling-right coalition -- of which it is a member -- may collapse because of the refugee children debate underway in the country, and the coalition has proposed a new federal anti-begging law in a purported attempt to thwart Roma criminal groups that are moving into Norway. The ethnic Roma migrant population in Norway has increased by an order of magnitude since 2008. While the party does generally take a strong position on immigration -- thereby placing it within a nationalistic characterization, it has a history of weak platforms on other social and economic topics, leaving it typically in a centrist or even left-of-center position on many other issues.

Finland's nationalist party, the Finns Party (Perussuomalaiset), is strongly anti-immigration and opposes the adoption of Sharia law into judicial proceedings. The party has a left-of-center economic position coupled to a socially conservative policy. Since its founding in 1995 following the collapse of the Finnish Rural Party, the Finns Party has seen explosive electoral growth from 1% of the popular vote during the 1999 parliamentary elections, doubling to 2% in 2003, 4% in 2007, and more than 19% in 2011.

The Danish People's Party (DPP; Dansk Folkeparti) saw its primary growth between the 1998 and 2001 elections, moving up from 7% of the popular vote to 12.4%. Since 2001, the party's support at federal election time has stayed approximately constant at between 12.3% and 13.8%. This is yet another example of a European anti-immigration party often characterized as being on the "radical right," but whose economic policies would place it in the center or center-left of the political spectrum.

Despite its already strong anti-immigration policies, recent polling shows that "thirteen percent of voters in a recent poll said that Denmark needs a party even more critical of immigration than the Danish People's Party." Half of Danes want to limit the number of Muslims in their country while 7% said they want no Muslims whatsoever in Denmark. The DPP has even suggested that English stop being taught at Danish universities.

The increasing anti-immigrant sentiment in Scandinavia is being reflected in improved electoral results for the corresponding political parties, but beyond the tough positions on the immigration file, there are no general characteristics that bind these parties' histories and time lines for ascensions up the popular vote ladder -- nor even their placement on the political spectrum. There is certainly room for socio-economically conservative parties to tap more deeply into these widespread concerns over immigration and exploit them for political success at the ballot box. Lessons are also apparent for the right-of-center political parties in the United States and Canada -- both of which have been far too accommodating on immigration in recent years.