Together with other Slovene intellectuals in the 1980s, initiated and edited the alternative and dissident journal Nova Revija, which later became the platform for democratic reform in the Socialist Republic of Slovenia.
In 1987, he was among the authors of the Contributions to the Slovenian National Program, an intellectual manifesto that demanded a democratic, pluralistic and sovereign Slovenian state. The publication of the manifesto by the journal Nova revija, edited by Rupel, caused a huge scandal in Yugoslavia, and Rupel was forced to step down as editor. In 1989, he was one of the founders of the Slovenian Democratic Union (Slovenska demokratična zveza, SDZ), one of the first parties that opposed Communist rule.
After the victory of the anti-Communist DEMOS coalition in the first free elections in Slovenia in 1990, Rupel was appointed as State Secretary for International Cooperation in the cabinet of Lojze Peterle, thus becoming de facto the first foreign minister of the Republic of Slovenia, which was then seeking independence from Yugoslavia. During his term in office, Slovenia declared its independence and gained international recognition. Rupel also remained in office during the first centre-left coalition government led by Janez Drnovšek.
In 1991, the Slovenian Democratic Union suffered an internal split: Rupel led its left-wing fraction, formed among others by Jelko Kacin, Igor Bavčar, and France Bučar, into the formation of a new party, called the Democratic Party. The same year, he was elected its president. In the elections of 1992, the new party suffered a defeat, but Rupel managed to be elected a representative in the National Assembly of Slovenia. In 1994, most of Rupel's party merged into the Liberal Democracy of Slovenia party, led by Janez Drnovšek. In 1994, he ran for mayor of Ljubljana and took office in 1995. He remained in this position until 1997, when he was appointed ambassador to the United States.
During 2005 he was the chairman-in-office of the OSCE.
In 2008, after the victory of the centre-left coalition led by Borut Pahor, Rupel was replaced as foreign minister by Samuel Žbogar. However, he was nominated by newly elected Prime Minister Borut Pahor as his personal Special Envoy for Foreign Affairs.
Rupel is the uncle of the Slovene pop-singer Anja Rupel.
He was married to Marjetica Ana Rudolf Rupel until her death in 2022. She was previously married to Slovenian singer Lado Leskovar. Her father was Janko Rudolf, Slovenian partisan, People's Hero and politician.[4]
^ abStanko Janež (1971). Živan Milisavac (ed.). Jugoslovenski književni leksikon [Yugoslav Literary Lexicon] (in Serbo-Croatian). Novi Sad (SAP Vojvodina, SR Serbia): Matica srpska. p. 465.