The 1968 student leader, turned German Green, turned French Green, has caused havoc in the ranks of Lionel Jospin's pink-red-green coalition in the last two weeks.
Mr Cohn-Bendit, 53, a German Euro MP, was chosen last month to lead the list of the French Greens in next June's European elections. Since then, a series of acerbic, and amusing, comments in favour of a federal Europe, free markets, illegal immigrants and soft drugs but against nuclear power and traditional left-wing thinking has sent green cannoning violently against red and pink.
Robert Hue, the Communist Party leader, says there is a "real danger" of the coalition coming apart if Mr Cohn-Bendit is not ordered to play by the polite rules of coalition politics. Leaders of the radical, Eurosceptic wing of the Socialists described him at the weekend as a "buffoon" and a "radish" - red on the outside, white (that is, blank) inside.
In an attempt to defuse the tension, Mr Cohn-Bendit invited Mr Hue to dinner in Paris last night. Mr Hue accepted but nervously hoped his host had not invited the press.
If the Greens exceed the 5 per cent minimum vote for winning seats in Strasbourg, Mr Cohn-Bendit will become the first politician to be elected to the European Parliament from two different countries. He has set himself, and the French Greens, two far more ambitious targets.
First, he wants to supersede the Communists as the second force on the French left (which would require about 8 or 9 per cent). Second, he would like to beat Jean-Marie Le Pen's far-right National Front (which would require about 15 per cent).
Mr Cohn-Bendit is a German citizen, born in France in 1945 of German- Jewish parents. He is running in France next year under the European Union rule that allows any EU citizen to stand in a European or local election anywhere in the Union.
On 21 May 1968, three weeks into the student protests, Mr Cohn-Bendit was taken to the German border and banned from France. He settled in Frankfurt and became a teacher, an ecologist, a local government official and a Green MEP.
As energetic and plausible as ever, Mr Cohn-Bendit says that he wishes to take the European debate away from the tired ground of Brussels bureaucracy and the dangers of the single currency (which he supports). He wants to focus on Europe as a force for economic, social and personal freedom: "une idee jouissante de l'Europe" - a "joyful" or "orgasmic" idea.
The former left-wing rebel believes in free markets; more flexibility at work; open European borders; reduced taxes and the privatisation of nationalised industries. But he also believes in a generous degree of legalisation of illegal immigrants; the abandonment of nuclear power; the legalisation of soft drugs and a solid, minimum welfare net for all.
Opinion polls suggest that Cohn-Benditisme, vintage 1998, appeals to young French people as much as the 1968 variety - precisely because it breaks away from the traditional language and ideological categories of both left and right. One survey, admittedly six months before polling day, gave him 9 per cent of intending voters, three times the Greens' score at the last European elections.Reuse content