France's National Front has long been anti-euro as well as anti-immigrant, and Marine Le Pen's stand against the single currency contributed a lot to her strong showing in the first round of the presidential election.

ECONOMIST: The euro crisis

And although Mr Le Pen is having trouble getting 500 signatures, it seems inconceivable that he will not stand.

ECONOMIST: The French presidential race

Fact: the ethic of the immigrant is and always has been to stand for hard work and family values (the latter something for which M Le Pen rather ironically claims to be the champion).

BBC: Le Pen: Is Europe next?

Mr Melenchon says he will stand in the working-class town of Henin-Beaumont, near Calais, where Ms Le Pen resides.

BBC: French leftist Jean-Luc Melenchon to challenge Le Pen