The Social Democratic Union () was founded in 1992, following Croatian independence, being one of very few political parties to identify itself as left-wing. Most of their members were former Communists or left-wingers displeased embracing Croatian nationalism, the excesses of privatisation and human rights abuses of ethnic minorities. The first leader of the party was Branko Horvat, noted economist and one of the few Croatian intellectuals to oppose the dissolution of SFR Yugoslavia. In the early 1990s, the SDU was also one of the few political parties to openly advocate co-operation and integration of Croatia with other republics of former Yugoslavia, a view very different from the current Croatian political mainstream. In the 1992 parliamentary elections it turned out that SDU nevertheless enjoyed some degree of support, especially among ethnic Serbs living in government-controlled territories. Although it failed to break the 2% vote threshold of entry into the Croatian Parliament, the SDU could have hoped to win three seats by fulfilling the constitutional quota of ethnic Serbs in Sabor. Instead, the Croatian Constitutional Court, in one of the most controversial decisions in their history, ruled that the seats should go to Serb People's Party as an "ethnic party", and presumably the only true representative of ethnic Serb minority, despite the fact SNS won fewer votes than SDU.