"Spikes in electoral success should not be confused with policy influence," Banulescu-Bogdan said. "Even parties that have gotten more than 10 percent of the vote have not necessarily been successful in restricting immigration policy."
"Many [radical right parties] have campaigned on anti-establishment, anti-EU, or anti-Muslim platforms," Banulescu-Bogdan said.
She noted, however, that although the United Kingdom right-wing Independence Party (UKIP) received nearly 27 percent of the vote in the 2014 European Parliament elections, it only managed to secured 1 seat in the subsequent 2015 British national elections.
"While several far-right or populist parties obtained dramatic gains in the 2014 European Parliamentary elections, it remains to be seen whether or not these parties will have longevity on the European stage," Banulescu-Bogdan concluded.
Apart from UKIP, France's far-right Front National and Spain's anti-austerity Podemos parties have put in strong performances at local elections.