The protesters probably don't know that Socialists in France still consider Barack Obama exemplary. Is there a misunderstanding? ...
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I was curious about this too. So I went through some of the better known french political officials from Mitterand to Sarkozy on wiki. They are all slime all the time. Compared to his french counterparts, Obama does come out less disgusting. And there seems to be a similar blackmail going on. Vote for me, because if you don't Jean-Marie Le Pen will get to power. And indeed Le Pen is a lot more scary than his twisted stupid US far right like Gingrich. In one run off between Le Pen and Lionel Jospin, a million people protested against Le Pen, chanting `vote for the crook, not the fascist...'' Pretty funny.
Anyway the word Left in the title refers to the official organized left parties. And yes they were and are in government and that does no good because they all seem to be firmly entrenched in the neoliberal order.
CG