The post-World War II Sabor developed from the National Anti-fascist Council of the People's Liberation of Croatia (ZAVNOH), formed in 1943. In 1945, ZAVNOH transformed itself into the National Sabor of Croatia, preserving the continuity of Croatian sovereignty. After the war, the Communists ran unopposed in the 1945 elections; all opposition parties boycotted the elections due to coercion and intimidation by the OZNA secret police and the Communist Party, aimed at eliminating electoral dissent. Once in power, the Communists introduced a single-party political system, with the Communist Party of Yugoslavia (from 1952 the League of Communists of Yugoslavia) as the ruling party and the Communist Party of Croatia (from 1952 the League of Communists of Croatia) as a branch party. In January 1990, the Communist Party fragmented along national lines, with the Croatian faction demanding a looser federation. During Communist rule, the Sabor went from a unicameral parliament as specified by the 1947 constitution, to bicameral in 1953, changing again in 1963 to as many as five chambers and then to three in 1974. The constitutional amendments of 1971 established the Presidency of the Sabor, and one of its functions became representing Croatia, as the Yugoslav constituent republics were essentially viewed as nation-states generally surrendering only their foreign and defence policies to the federation; the federal bodies were no longer independent of, but instead formed by, the republics (after 1974 constitution, this role was taken by newly formed Presidency of the Republic elected by the Sabor).