The Republic of the Sudan was established as an independent sovereign state on 1 January 1956 upon the termination of the condominium of Anglo-Egyptian Sudan, over which sovereignty had been vested jointly in Egypt and the United Kingdom. Before 1955, however, whilst still subject to the condominium, the autonomous Sudanese government under Ismail al-Azhari had temporarily halted Sudan's progress toward self-determination, hoping to promote unity with Egypt. Despite his pro-Egyptian National Unionist Party (NUP) winning a majority in the 1953 parliamentary elections, however, Azhari realized that popular opinion had shifted against such a union. Azhari, who had been the major spokesman for the "unity of the Nile Valley", therefore reversed the NUP's stand and supported Sudanese independence. On December 19, 1955, the Sudanese parliament, under Azhari's leadership, unanimously adopted a declaration of independence that became effective on January 1, 1956. Azhari called for the withdrawal of foreign troops, and requested the governments of Egypt and the United Kingdom to sponsor a plebiscite in advance. Politics of independence Sudan achieved independence without the rival political parties' having agreed on the form and content of a permanent constitution. Instead, the Constituent Assembly adopted a document known as the Transitional Constitution, which replaced the governor-general as head of state with a five-member Supreme Commission that was elected by a parliament composed of an indirectly elected Senate and a popularly elected House of Representatives. The Transitional Constitution also allocated executive power to the prime minister, who was nominated by the House of Representatives and confirmed in office by the Supreme Commission. Although it achieved independence without conflict, Sudan inherited many problems from the condominium. Chief among these was the status of the civil service. The government placed Sudanese in the administration and provided compensation and pensions for British officers of the Sudan Political Service who left the country; it retained those who could not be replaced, mostly technicians and teachers. Khartoum achieved this transformation quickly and with a minimum of turbulence, although southerners resented the replacement of British administrators in the south with northern Sudanese. To advance their interests, many southern leaders concentrated their efforts in Khartoum, where they hoped to win constitutional concessions. Although determined to resist what they perceived to be Arab imperialism, they were opposed to violence. Most southern representatives supported provincial autonomy and warned that failure to win legal concessions would drive the south to rebellion. The parliamentary regime introduced