 The antagonism between a centralized Yugoslavia supported by Serbian nationalists and a decentralized Yugoslavia supported by Croatian and Slovenian nationalists was the main cause of unstable governance in Yugoslavia during the interwar period.In 1920, the centralized vision of Yugoslavia as supported by Serbian nationalists was enacted in the Constitution of the Kingdom of Serbs, Croats, and Slovenes passed on Serbian national and religious holiday Vidovdan (Saint Vitus Day) that became known as the "Vidovdan Constitution" or "St. Vitus Day Constitution" (Видовдански устав / "Vidovdanski ustav").Antagonism which rose between Serbian nationalists versus Croatian and Slovenian nationalists culminated in the 1928 assassination of Stjepan Radić on the floor of the Yugoslav parliament and the subsequent deterioration of parliamentary democracy in the country.