Election observers in Sudan say this week's voting has been mostly peaceful but remains plagued by logistical problems, especially in the south.
Reports of polling stations opening late, a lack of voting materials, and missing names on voter lists continued coming in on Tuesday, the third day of voting in the African nation.
VOA Swahili Service chief Mwanmoyo Hamza, who is in the city of Juba, reports that some people have waited up to three hours to vote while election workers sort out mix-ups.
He says in some instances, people spent six hours traveling between polling stations after their designated voting site was changed.
Former U.S. President Jimmy Carter, who is leading an observer mission, told reporters that there are faults in the voting but that it is too early to judge the entire process.
Voting was originally due to end Tuesday but was extended two days by Sudan's national elections commission.
Several opposition parties are either fully or partially boycotting the elections, saying President Omar al-Bashir and his National Congress Party have taken steps to rig the outcome.
These are Sudan's first multi-party elections since 1986. They are a key part of the 2005 peace deal that ended Sudan's north-south civil war.
That deal calls for another vote next year in which the south, which now has partial autonomy, will decide on whether to become fully independent.
The south's main party, the Sudan People's Liberation Movement, is boycotting this week's presidential race and most other races in the north. That makes it more likely that President Bashir will win re-election.
Mr. Bashir has ruled Sudan since seizing power in a 1989 coup. He is wanted by the International Criminal Court for alleged war crimes in Sudan's Darfur region.