A former member of the French Socialist Party, Allègre is better known to the general public for his past political responsibilities, which include serving as Minister of Education of France in the Jospin cabinet from 4 June 1997 to March 2000, when he was replaced by Jack Lang.
In the run-up to the 2007 French presidential election, he endorsed Lionel Jospin, then Dominique Strauss-Kahn, for the Socialist nomination, and finally sided with the ex-Socialist Jean-Pierre Chevènement, against Ségolène Royal.