A prominent opponent of Slobodan Milošević's government in the late 1990s, Kovačević was the leader of the League for Šumadija (Liga za Šumadiju, LZŠ) and served in the National Assembly of Serbia from 2001 to 2004.
In August 1991, following the start of the Croatian War, he organized the only peace concert in Serbia, with singers and actors from throughout the fragmenting country of Yugoslavia.
[3] Kovačević joined with Ivan Đurić (then living in exile in Paris) to create the Movement for Democratic Freedoms (Pokret za demokratske slobode, PDS) in the 1990s.
[6] He organized a petition drive in Kragujevac for the dismissal of Yugoslavian president Slobodan Milošević from office in June 1999, after the conclusion of the Kosovo War.
[8] The SDP participated in a broader opposition movement called the Alliance for Change during this time, and Kovačević organized a number of public rallies in Kragujevac against Milošević.
[9] The League for Šumadija joined the Democratic Opposition of Serbia (Demokratska opozicija Srbije, DOS), a diverse coalition of parties opposed to the Milošević administration, in 2000.
The League for Šumadija continued its membership in the DOS, and Kovačević appeared on the alliance's list, in the eighteenth position, as the sole representative of his party.
Kovačević appeared in the lead position on the ZZT list, which narrowly missed the electoral threshold to win representation in the assembly.
[26] In October 2004, Kovačević said that Internal Affairs minister Dušan Mihaljović had informed the DOS of the existence of mass graves in Serbia, resulting from the country's involvement in the Yugoslav Wars of the 1990s.
"[27] The LSV and the League for Šumadija participated in the 2007 parliamentary election on the list of the Liberal Democratic Party (Liberalno demokratska partija, LDP), and Kovačević was awarded the 101st position.