Zimbabwe awaits the results of a referendum for a new constitution that would limit the terms of a president for the first time in the country's history.
The proposed constitution would allow presidents to serve only two five-year terms.
Eighty-nine-year-old President Robert Mugabe and his rival, Prime Minister Morgan Tsvangirai, both supported the draft constitution, so it is expected to be approved. Authorities say they expect the official results of Saturday's referendum within the next several days.
Mr. Mugabe has ruled Zimbabwe for more than three decades, and even under the new constitution, he could remain on the job another 10 years, if re-elected.
Prime Minister Tsvangirai says the new constitution will provide proper checks and balances in the government.
"This is a new political dispensation. And I hope it is setting a new political culture: from the culture of impunity to the culture of constitutionalism.''
The two men entered into a power-sharing agreement to govern Zimbabwe following deadly violence that marred elections in 2008, but they have remained at odds. Scattered violence has occurred ahead of Saturday's referendum.
The new constitution would clear the way for presidential and parliamentary elections later this year, ending the power-sharing deal and curbing some presidential powers. A new constitution would replace the 1980 blueprint written for the country when Zimbabwe gained its independence from Britain.