While at Stora, Mann served as a shop steward with Local 972 of the Canadian Paperworkers Union.
During his municipal service from 1985 to 1988, Mann served as Deputy Warden and on various council committees.
On June 11, 1993, Mann was appointed to the Executive Council of Nova Scotia as Minister of Transportation.
Mann briefly re-entered politics when on July 30, 2004 he announced his candidacy for the leadership of the Nova Scotia Liberal Party.
[6] Mann was defeated in his bid for the leadership at the convention that October by Francis MacKenzie.