[gutnor]

Also more importantly, the FN is eurosceptic, or more precisely keen on France sovereignty.

Since the crisis, Euro skepticism sentiment is quite strong in Western Europe. The handling of the Cyprus, Greece, ... has split in people mind Europe, the region and Europe, the political construct. So even people very pro Europe as an identity are against Europe as currently implemented ( that is quite striking in my circle of all expats friends ). Parties like the FN are boosted by the traditional extreme-right voters, the traditional eurosceptics now joined by those Euro disappointed.

ISIS and the refugees is yet another botched handling by Europe (regardless if you want to help or want to keep them away, the handling is a disaster). The anger of the attack followed almost immediately by an election has probably tilted the balance for a lot of people.