Chad's president, one of Africa's longest-serving leaders, is seeking re-election for a fifth term when voters go to the polls on 10 April. President Idriss Deby Itno has been in power for 26 years.
President Deby came to power through a military coup in 1990. He has maintained tight control over key state institutions and is a strong ally of the West in regional counter-terrorism operations.
The opposition boycotted the last election in 2011, allowing him an easy victory. This year, his chances of winning again are strengthened by fractures in the opposition. In addition, the constitutional council has barred Mr Deby's staunch critic and prominent opposition activist Ngarlejy Yorongar, along with five other aspirants.
There are now 13 candidates challenging the president.
In February, the rape of the teenage daughter of opposition presidential candidate Mahamat Brahim Ali led to angry protests, which prompted the president to sack members of his cabinet.
The extension of a state ban on protests in March spurred further unrest, including an indefinite general strike which paralysed state operations.
Security forces also arrested opposition activists for organising a protest rally in which demonstrators were asked to blow whistles to urge Mr Deby to step down.
Who are the main candidates?
President Deby is representing the Patriotic Salvation Movement. He has won by landslides in the first round of every presidential poll, except the first multi-party elections in 1996. Two of his closest challengers this year are former ministers in his government.
Saleh Kebzabo, the leader of the National Union for Development and Renewal group, trained as a journalist and served in ministerial positions under President Deby between 1993 and 2001. He twice attempted to unseat Mr Deby - in 1996 and again in 2001 - but came third on both occasions.
Joseph Djimrangar Dadnadji served as prime minister from 2013-15 before resigning and forming the Popular Action Framework for Republican Solidarity and Unity party.
How does the voting system work?
Presidential candidates need to get more than 50% of the vote in order to win.
If there is no clear winner in the first round, the two leading candidates face off in a second round vote determined by a simple majority. The opposition feel they stand a good chance of winning if a second round of voting is required.
The poll will be conducted by the national independent electoral commission and supervised by the interior ministry. International poll monitoring bodies are expected to deploy observers.
What are the main issues?
Chad has experienced waves of instability and violent conflict since independence from France in 1958.
In recent years, domestic crises have been compounded by threats from neighbouring countries. These threats include attacks by Nigeria's Islamist group, Boko Haram, and al-Qaeda in the Islamic Maghreb (AQIM).
Despite the country's oil wealth, most Chadians live in poverty. Record low international oil prices and the growing cost of anti-terror operations in the region threaten to make the situation worse.
Delays in payment of civil servants' salaries and a subsequent recruitment freeze have prompted anti-Deby protests over the past three months, despite a violent state crackdown.
The opposition views Mr Deby's departure as the only solution.