There is no one country in the EU that has not seen the recent rise of movements combining populism and nationalism, although with different success and different political impact. Even separatist movements, like in the Scottish case, can be considered as belonging to this category.
The populist component of these movements expresses a profound distrust vis-à-vis the power élites and calls directly to the people, as the depository of popular sovereignty and final source of legitimation. Distrust concerns the entire establishment, not only politicians and parties, but also the “Brussel’s burocracy”, the technocrats, the big financial circles, the banks, the multinational corporations, etc. The deep fall of trust is rather generalized, it is more strongly visible however where the financial and economic crisis has hit more severely. Distrust, as I said, involves the whole ruling class and, in particular, the entire political class, right and left, there are no distinctions, like in the slogan “all politicians are the same”. The political struggle is either "facade" (“They pretend to fight each other, however under the cover they do agree and divide the loot, which is the product of our work”), or is an expression of the inability to “agree” (“They are capable only to quarrel”). Public sentiments are often contradictory.
Distrust increases with the “fears” caused by the crisis. The “populists” are in need of “fear”, are in fact the “entrepreneurs of fear” and appeal to those who have lost what (little or much) they had and to those who are afraid of losing what they have, or are afraid of not getting what they expected to have in the future. The very poor generally do not have fear because they are used to live day by day with the little they can get from public charity. Populism grows in the ground of those who are “at risk of poverty”, mainly in the lower layers of the middle classes. Political crises weaken traditional memberships, make behaviour fluid, fluctuating and erratic, therefore hardly predictable. Even voting behaviour. This explains why authoritarian and totalitarian regimes frequently enjoy a broad popular support and are even democratically legitimated by electoral successes.
The fact that populism melts with nationalism depends on the historical context of globalization, of which Europeanization is one aspect. In the face of fire, or of the abyss (the metaphors of crisis) fear induces to make a step backward, toward a nation that has been “betrayed”, or to an imaginary nation which never existed, but that promises to be capable of being “re-born”
In Eastern European countries you need to consider also the consequences of the implosion of the Soviet empire, that had frozen the nationalities without being able to overcome them. Many countries have not yet fully recovered from the fall of the planned economy, that produced a serious social crisis (e.g. problems of health, alcoholism, unemployment, etc.). In Western countries, the downsizing of welfare policies (health, pensions, education in some cases) should be taken into account. Immigration is perceived as a threat (generating problems of housing, health care, illegality, but also the perceived danger of religious contamination).
In short, there are favourable conditions for the explosion of populist/nationalist movements unclassifiable in terms of right or left. In some states democracy will be able to withstand the threat and face the challenge, in others there is the risk of drifting toward undemocratic outcomes. The risk does not mean that these movements are doomed to win and will overwhelm the defences. Even Hitler and Mussolini could have been stopped, if the opponents had been aware of the threat and capable to act at the right time. If they are going to win it will not be (only) because of their strength, but mainly because of the weakness of their opponents, the defenders of democracy, their inability to give convincing answers to the crisis. We may ask ourselves what would happen if some countries (like Italy, as advocated by some populists) decide to exit from the Euro. The scenarios, I suppose, would be catastrophic: incapacity to pay back the public debt, or the need to repay the debt in a revalued currency; inability to use new debt to finance the growing deficit; probability of reintroducing barriers to free trade; general impoverishment of Europe as a whole; loss of political influence at international level; likelihood to become more easily prey to the most rapacious forms of global capitalism.
The only solution I see for Europe is to strengthen and democratize the EU, not to build a super-state, but to mitigate its internal imbalances in order that they do not become explosive.