President Deby wants to run for a third term
Voters in Chad go to the polls on Monday to decide if President Idriss Deby can stand for a third term in 2006. Under the current constitution a president can serve only twice. Opposition parties have called for a boycott, saying a "Yes" vote will give Mr Deby too much power.
What is behind the move?
President Deby, who has run the country since 1991, said during his last election campaign he had no intention of changing the constitution.
While he has not commented on his apparent change of heart, observers have pointed to a number of ways he could benefit.
Some argue he wants to ensure power stays in his native eastern Chad, by staying on himself or grooming one of his sons as a successor.
But in an interview with French radio in January, he denied he had his son Brahim in mind.
What about the crisis in neighbouring Darfur?
The bid to extend the presidential tenure has also been linked to the conflict in Sudan's Darfur region.
The fighting there has left President Deby vulnerable, especially after the killing of his members of Zaghawa community by Sudanese Arab Janjaweed militias.
The attacks are said to have divided Chad's army, with some Zaghawa officers calling for a firmer line against Sudan.
Some 200,000 refugees have crossed from Darfur into Chad.
Will the vote be fair?
Some observers believe France and the US could turn a blind eye to any irregularities, because Mr Deby has presided over one of the most stable periods in the country's recent history.
France has a military garrison in Chad, while Washington says Chad has proved "a valuable partner in the global war on terror".
International pressure forced Mr Deby to introduce greater democracy and he won the country's first multiparty presidential elections in 1996. He was re-elected in 2001.
The election commission head, Djimtibaye Lapia, has urged all parties to ensure the campaign (6 May - 4 June) is "healthy and free of hitches".
What is the procedure?
The country's National Assembly has already approved constitutional amendments allowing the president to stand again.
This and other constitutional changes were put to the house in May 2004 by the ruling Patriotic Salvation Movement (MPS), which has a clear majority: 113 out of 155 MPs.
The vote was unanimous after opposition MPs walked out.
But the changes must be ratified in this referendum, which state radio has trumpeted as "unquestionably" the main political event of the year.
Some 5.3m Chadians are eligible to vote.
Are there precedents?
This is Chad's third referendum since independence from France in 1960.
The first, in 1989, saw former President Hissene Habre's term extended and the endorsement of a single party state. Some 93% of the 2.7m voters backed the changes.
The second was called by Mr Deby himself in 1996 and sought approval for a presidential term of five years. About 64% voted in favour.
What else is being voted on?
Other proposed changes include replacing the Senate or upper house with an Economic, Social and Cultural Council.
There is also a clause which would make constitutional revisions a presidential prerogative.
What does the opposition say?
In April exiled opposition figure Ahmat Soubiane, a former interior minister, told French radio the vote was a "plan to offer life presidency" to Mr Deby.
Several parties have urged a boycott, including the Rally for Democracy and Progress (RDP).
RDP Chairman Lol Mahamat Choua has urged supporters to observe a "national day of mourning".
Is there much security?
A special police unit set up with the help of the French government will provide security.
Human rights groups and the opposition say the unit's true mission is to repress the people if they dare show discontent.
What has the media been saying?
Chad's media regulator has issued guidelines on how to cover the poll.
State radio was allowed to air party broadcasts for five days a week and national TV for four days a week during May.
The regulator banned private and community radios from airing political debates or commentaries during the campaign period.
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