But here's what we've been saying for years—if major parties don't like the "far right" they need to stop censoring normal attitudes toward immigration. See, for example, How PC Boosts Le Pen, By Theodore Dalrymple, City Journal, April 25 2002, The subhead is "The French demagogue won by addressing reasonable concerns about Arab immigration and French identity that other politicians ducked." And if any major party will do something about immigration, as Sarkozy has promised to do, then they'll get a lot of support.
Le Pen has always been something of a fringe character, but for immigration skeptics he was the only game in town. To the extent that Sarkozy took away his votes, he did so by adopting Le Pen style policies.