They will also vote for members of the 450-seat National Assembly and governors for the county's 25 states, as well as members of state assemblies.
Voters in the semi-autonomous southern region will additionally elect a president of the South Sudan government and members of its 171-seat Assembly.
When President Omar Hasan al-Bashir seized power following a bloodless coup in 1989, the activities of all political parties and trade unions were frozen for 10 years. Moves towards the restoration of democracy led to the registration of political parties from 1999. Most opposition parties however boycotted the 2000 elections in which Mr Bashir was declared winner amid widespread claims of rigging. MORE HERE