Though recent opinion polls have consistently been against her getting past the centrist Emmanuel Macron to the Élysée Palace, the very fact that an openly xenophobic, anti-immigrant and anti-European Union politician is on the final ballot speaks to a great and troubling fracture in French society.
So how and why have so many people been persuaded to back her?
Though she has now, temporarily, stepped down as leader of her party, her affiliations are in no doubt.
The conundrum remains: how has someone who for years has been so identified with far-right chauvinism and exclusion managed to give her party an acceptable face and get within touching distance of the presidency?
French producers Charles Emptaz and Claire Billet, who usually spend their professional lives covering foreign stories far from home, were as puzzled by these questions as we were, so several weeks ago we sent them behind-the-scenes on the campaign trail to investigate.
