A native of Bosnia and Herzegovina, Kovačević earned a Ph.D degree from the University of Vienna. He entered Croatian politics in early 1990s as one of the most prominent members of the Croatian Christian Democratic Union (HKDU). He was outspoken critic of Franjo Tuđman and his handling of war in Bosnia and Herzegovina. As a member of opposition alliance that included the left-wing Social Democratic Party of Croatia (SDP), he entered the Croatian Parliament in 1995.