There is a new research paper on this topic, from Ernesto Dal Bo, Frederico Finan, Olle Folke, Torsten Persson, and Johanna Rickne:
We study the rise of the Sweden Democrats, a radical-right party that rose from negligible size in 2002 to Sweden’s third largest party in 2014…We take a starting point in two key economic events: (i) a series of policy reforms in 2006-2011 that significantly widened the disposable-income gap between “insiders” and “outsiders” in the labor market, and (ii) the financial-crisis recession that doubled the job-loss risk for “vulnerable” vs “secure” insiders. On the supply side, the Sweden Democrats over-represent both losing groups relative to the population, whereas all other parties under-represent them, results which also hold when we disaggregate across time, subgroups, and municipalities. On the demand side, the local increase in the insider-outsider income gap, as well as the share of vulnerable insiders, are systematically associated with larger electoral gains for the Sweden Democrats. These findings can be given a citizen-candidate interpretation: economic losers (as we demonstrate) decrease their trust in established parties and institutions.
Is it being an economic loser that makes you support the Sweden Democrats, or simply observing a lot of economic losers around you, the latter having been the case for Donald Trump’s support? This Twitter thread gives some key pictures from the paper and summary of results.