Answer: the groups that are mostly supporting this kind of movement are the anti-euro, xenophobes, anti-Islam, neo-Nazists, far-right parties, primarilly composed by men from middle classes.
These groups have a sense of belonging to their countries and feel that the foreigner is a threat to their culture and economy, as well as their safety. Therefore, they start to join far-right parties or follow politicians that declare themselves against other people's cultures and countries, because the strenght must be inside their own. The struggles that middle class workers have gone through are also another excuse for the hatred they feel for anyone that comes to their jobs and "take their places" for less money than they ask for, stating that these are the responsible for the decreasing wages. They link crime and poverty to immigrants, as well.