Despite the growing attention to the performance of anti-system parties in the next European elections, Matthew Goodwin in the New Statesman argues that other elections should be watched closely in 2014:
Around the same time as the European elections are local elections in Greece across over 300 municipalities as well as a highly symbolic Mayoral election in Athens that Golden Dawn plans to contest.
National elections will also take place in Hungary in the Spring and in Sweden in September. Background on past and upcoming elections can be found in the IFES Election Guide and at Norwegian Social Science Data Services.
An evidence-based look at the prospects of anti-system parties in the next European elections is in this post from a couple of months ago by Cas Mudde, who has written extensively on populism and euroscepticism.