Kammala jumla mai zuwa: A cikin 1989, Janša ya shiga cikin kafa ɗaya daga cikin jam'iyyun adawa na farko a Slovenia, Ƙungiyar Democrat ta Slovenia (SDZ) kuma ya zama mataimakin shugabanta na farko, kuma daga baya shugaban majalisar jam'iyyar. Bayan zaɓen farko na 'yanci a watan Mayu na 1990 ya zama Ministan Tsaro a cikin majalisar Lojze Peterle, matsayin da ya riƙe a lokacin mulkin mulkin mallaka.
Yakin Slovenia don 'yancin kai a watan Yuni da Yuli 1991. Tare da Ministan Cikin Gida Igor Bavčar, Janša shine babban mai shirya dabarun Slovenia game da Sojojin Yugoslav.