Zimbabwe's President Robert Mugabe and Prime Minister Morgan Tsvangirai are each predicting outright wins as voters cast ballots Wednesday in presidential and parliamentary elections.
The two rivals are the leading contenders in a presidential race with five candidates that has brought long lines of voters to polling sites.
Prime Minister Tsvangirai is trying for the third time to unseat Mr. Mugabe, and has accused the president's party of trying to steal the election. Rights groups and critics have made similar allegations.
Mr. Mugabe denies taking part in any vote-rigging. He has ruled the country since its 1980 independence, and has pledged to respect the vote.
The country's election commission has until August 5 to release the results.
The two men have led Zimbabwe through a fragile power-sharing government they set up in the wake of the last polls in 2008. That election ended with Mr. Tsvangirai disputing the results, and a round of unrest that left 200 of his supporters dead.
The United States expressed concern about partisan behavior by state security institutions, as well as technical and logistical issues that could keep Wednesday's vote from being transparent and credible.
Western observers have been barred from the election. About 7,000 domestic monitors and several hundred others from elsewhere in Africa will observe the proceedings.