Parliamentary elections were held in 1920, 1923, 1925 and 1927, while with the new constitution a de facto Lower and Upper House were introduced in 1931 (the Senate next to the National Assembly).
Having run nearly unopposed in that election, CPY promulgated a new Constitution in 1946 that abolished the monarchy and transformed the country into a federal republic.
The Federal Council was elected by a complicated indirect delegate system through the popular front Socialist Alliance of Working People of Yugoslavia.
Over the course of 1990 each constituent republic adopted democratic constitutions which allowed for political parties other than the League of Communists, and subsequently held multi-party elections.
These were held in each of the constituent republics: According to results, support for the former member parties of the League of Communists of Yugoslavia on the federal level at that point was between 35 and 40%.