From 1992 to 1994 was director of Il Popolo, the newspaper of his party, and after Italian referendums, 1993 he wrote the new electoral sistem act. After the 1996 general elections he was President of Italian Popular Party parlamentarian committee; when Massimo D'Alema became new Prime Minister, Mattarella was named as his vice-premier. In 1999 he became Defense Minister and kept this position under Giuliano Amato second government. He was re-elected in 2001 and 2006 general elections.