In France, the regional elections in late 2015 saw the FN win a majority of seats all over the country. Both the socialist party and the republicans lost most of the contested areas, and it became clear that the FN is the biggest party in France. However, the repercussions of this grand victory did not help Marine LePen's prospect for the presidential elections in 2016.
As her party now had actual power, all eyes were on France to see how the anti-EU, anti-immigration far-right that was springing up all over Europe would handle being in office. As it turned out, they did not handle it very well.
The sudden and aggressive cuts in funds to immigration management and social welfare caused a stir of social unrest as early as February 2016. The tensions with the EU meant that international trade became rocky. The FN tried to salvage the french economy by making new deals with Russia, but this caused them to be the subject of sanctions by the US, as tensions over Ukraine and Syria resurfaced. And the party's support plumetted.
All in all, voting for the FN in the regional elections seems to have been the surest way to keep them from the presidential office.