Well, remember less than 17% of those voting opted for Le Pen, and presumably they're not the people protesting. Possibly, the demonstrators are partly objecting to a voting system which allows 16 candidates to stand in the first ballot, and then goes directly to a final vote between the top two candidates. But nevertheless to a large extent the leftist French electorate and parties have only themselves to blame for Le Pen's success - (a) for not fielding fewer candidates, and (b) for not voting in larger numbers.