to govern effectively due to Chiang pulling the strings behind government as Director-General of the Kuomintang. With the fall of Nanjing to the PLA in April 1949, the ROC government moved south to Guangzhou, and then to its wartime capital of Chongqing, and finally to Chengdu. Sensing that he would eventually lose the mainland to the communists, Chiang secretly started preparations to move the government to the island of Taiwan, which was placed under the ROC's control on 25 October 1945. Taiwan was seen as a safe haven for Chiang due to it being separated from the mainland by the -wide Taiwan Strait. During that period, more than two million civilians, military personnel and government officials left the mainland for Taiwan. Chiang then declared Taipei as the provisional capital of the Republic of China on 7 December 1949, and left Chengdu for Taipei by air three days later when the city fell to the communists. Since 1949 Based on the Constitution of the Republic of China, the head of state is the president, who is elected by popular vote for a four-year term on the same ticket as the vice-president. The president has authority over the five administrative branches (Yuan): the Control, Examination, Executive, Judicial, and Legislative Yuans. The president appoints the members of the Executive Yuan as the cabinet, including a premier, who is officially the president of the Executive Yuan; members are responsible for policy and administration. Originally, the National Assembly of the Republic of China was elected in mainland China in 1947 to officially carry out the duties of choosing the president, to amend the constitution, and to exercise the sovereignty of the citizens, but in fact, the Assembly's role in Taipei seemed to reconfirm the executive powers of President Chiang Kai-shek. The National Assembly was re-established on Taiwan when the government moved. Because it was impossible to hold subsequent elections to represent constituencies in mainland China, representatives elected in 1947-48 held these seats "indefinitely." In June 1990, however, the Council of Grand Justices mandated the retirement, effective December 1991, of all remaining "indefinitely" elected members of the National Assembly, Legislative Yuan, and other bodies. In 2005, the National Assembly permanently abolished itself by ratifying a constitution amendment passed by the Legislative Yuan. Amending the ROC constitution now requires the approval of three-fourths of the quorum of members of the Legislative Yuan. This quorum requires at least