Zimbabweans vote Saturday on a referendum for a new constitution that, for the first time, limits the terms of a president.
The new proposed constitution allows presidents to only serve two five-year terms.
Eighty-nine-year-old President Robert Mugabe has ruled Zimbabwe more than three decades, and even under the new constitution, he could remain on the job another 10 years, if reelected.
Mr. Mugabe, and his rival, Prime Minister Morgan Tsvangirai, both support the draft constitution, and it is expected to be approved easily.
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. There have been various acts of violence 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.
Official results of the referendum are expected within five days.