He was a student leader during the unrest of May 1968 in France and was also known during that time as Dany le Rouge (French for "Danny the Red", because of both his politics and the colour of his hair).
Under studenteroprøret i Paris i maj 1968 var han en af studenterlederne, og blev i samtiden kendt som Dany le Rouge (fransk: 'Danny den røde'), dels på grund af sin politiske linje, dels på grund af sin hårfarve.