The established opposition, the centre-right Republican party, saw its chances sink on March 1st when its standard-bearer, François Fillon, revealed that he was being formally investigated for paying his wife and children nearly €1m ($1.05m) of public money for allegedly fake jobs.
In the face of high taxes and heavy regulation those with entrepreneurial vim have long headed abroad, often to London.
It collapsed in the face of massive strikes.
She has effectively distanced herself from her party’s anti-Semitic past (even evicting her father from the party he founded), but she appeals to those who want to shut out the rest of the world.
If she pulls France out of the euro, it would trigger a financial crisis and doom a union that, for all its flaws, has promoted peace and prosperity in Europe for six decades.