Stolfi was first elected to the Grand and General Council in 1983 and was reelected in 1988, 1993, 1998, and 2001. He served as Minister of Tourism, Commerce, Sport, and Agriculture from 1983–86; as Minister of Industry, Handicrafts, and Economic Cooperation from 1992–98; as Minister of Industry, Handicrafts, Economic Cooperation, Post and
Telecommunications from 1998–2001; as Minister of Internal Affairs, Civil Protection, and Post and Telecommunications from July 2001–June 2002; and as Minister of Finance and Budget, and Economic Programming, in relationship with the Philatelic-Numismatic Association, and Transport, from June 2002–December 2002. He was named Secretary of State for Foreign and Political Affairs on 17 December 2002, with 40% of the legislative vote in a cabinet reshuffle.
Politically, Stolfi served as General Secretary of the Unitary Socialist Party (1988–90; as Co-Secretary of the San Marino Socialist Party (1990–92); and, as of May 2003, as a member of the Socialist Party secretariat (1992–).