Many fear that the electorate and political parties may find it difficult to navigate the complex process of voting.
As the elections' nomination period starts, here are some key facts about the votes.
Elections were promised in the 2005 Comprehensive Peace Agreement that ended more than two decades of civil war between north and south Sudan.
Voting is due to take place over three days from April 11 2010, with the results out by April 18. But the poll has already been delayed several times.
If all goes to plan, it will be the oil-producing country's first full, multi-party poll in 24 years. There was an effectively single-party ballot in 1996 and most opposition parties boycotted elections in 2000.
Sudan's inexperienced voters will face one of the most complex elections on record with six different votes using three different voting systems.
Elections for the President of Sudan and the President of Southern Sudan will be decided by absolute majority -- the winner will have to get more than half the votes. If no one gets that many, there will be a second round of voting between the top two candidates.
If a northerner becomes President of Sudan, he has to nominate the south's president as his first vice president, according to the interim constitution . If a southerner wins, he has to appoint a northern vice president.
State governors will be chosen by relative majority -- the winner is the one with the most votes.
Voters will also choose members of Sudan's National Legislative Assembly, as well as state assemblies across Sudan. Southerners will also choose members of the Southern Sudan Legislative Assembly.
Most members of those assemblies will be chosen by relative majority voting, and will represent geographic constituencies. But there will also be a proportional system assigning 25 percent of the seats to women and 15 percent to other party candidates in each house.
Under this proportional system, voters vote for a party. Parties are then awarded seats according to the number of votes they get. They fill those seats from lists of women and other party candidates drawn up before the poll. FACTS AND FIGURES
Officials will have to transport up to 7.5 million kilograms of election material around the country, according to the United Nations mission in Sudan, which is assisting the country's National Elections Commission.
Officials will have to print more than 1,000 different kinds of voting form, to cover the different combinations of votes and candidates in each constituency.
Sudan's vast size is one of the biggest challenges facing officials. Officials have to arrange complex ballots across around 1.5 million square miles (2.5 million sq km) of mostly remote territory.
More than 16 million voters, around 80 per cent of the total electorate, registered to vote during November and the first week in December, said the National Elections Commission, although parties have said the registration was marred by fraud.
Those details are being entered into an electronic registry. Each registered voter should have received a laminated slip that should help them prove their place on the electoral register when they come to vote.
The Commission is still working out guidelines for the actual vote. Under one plan, staff may mark people's thumbs with indelible ink after they have cast their vote. (Writing by Andrew Heavens; Editing by Giles Elgood)
- Reuters - Thomson Reuters Foundation
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