I assume you're referring to the Sweden Democrats?
A chart of opinion polls on Swedish political parties from Wikipedia:
Sweden Democrats are the yellow line. Looks like they're gaining popularity, but are still well below the two dominant parties. It's going to take a bigger upswell than that to overthrow two entrenched parties, I imagine.
Of course, a parliamentary system is different from what we have in the US, but not so different that these guys have any real shot at controlling the country. Influencing things in a bad way, yes, but Nazi Germany, no.