|Rajoelina has been power since March 2009 after seizing power in a military-backed coup [File: EPA]
Madagascar will vote on Wednesday in a referendum on a new constitution, seen as a test of confidence on the current president.
Andry Rajoelina, who has been in power for more than a year after seizing power in a military-backed coup, could have his rule legitimised by the vote which the three main opposition parties have urged the public to boycott.
A change put forward in the new constitution states that the leader of the so-called High-Transitional Authority - that Rajoelina heads - will keep power until the election of a new president.
This could lead to Rajoelina keeping his position indefinitely, Johary Ravaloson, a writer and legal expert said.
"Because he's set no date for stepping down, nor spelled out conditions for the next elections," Ravaloson said.
About seven million people are registered to vote.
The nation of 20 million has been at political stalemate, with violence occasionally flaring, since Rajoelina's military-backed and widely denounced takeover in March 2009 sent President Marc Ravalomanana into exile in South Africa.
Rajoelina has refused to allow Ravalomanana to return. In August, a court Rajoelina established convicted Ravalomanana in absentia of conspiracy to commit murder and sentenced him to life in prison in a case related to the turmoil of the coup that toppled him.
Supporters of Ravalomanana and two other former presidents have called for a boycott of the vote.
Raharinaivo Andrianatoandro, president of a transitional legislature established by Rajoelina, said those who don't vote "have failed to understand the importance of this process".
Rajoelina accuses Ravalomanana, a wealthy businessman, of misuse of office and of being blind to poverty on the island famous for lemurs and other wildlife found nowhere else in the world, and the inspiration for two animated films of the same name.
Ravalomanana says his rival, a disc jockey-turned-entrepreneur, is a populist and rabble-rouser with little genuine interest in democracy.
The impasse has meant hardship for the impoverished Indian Ocean island.