Fifteen parties in Chad's fragmented opposition said on Tuesday that they had named a single candidate to contest presidential elections on April 11 against the 30-year incumbent, Idriss Deby Itno.
Their champion is Theophile Bebzoune Bongoro, a 55-year-old newcomer to politics, who was backed by nine out of the 15 party leaders, they said.
Five others voted for Deby's best-known adversary, Saleh Kebzabo, the runner-up in the 2016 elections with 12.8 percent of the vote.
Opposition parties last week set up a coalition called Alliance Victoire (Victory Alliance), seeking to overcome long-standing divisions that have helped Deby to remain in power.
Bongoro is a notary who has never taken part in any election. In 2018, he set up his own political movement, the Party for Assembly and Equity in Chad (PRET).
"We want power to be handed over democratically, through the ballot box," he said after being named candidate.
The ruling party, the Patriotic Salvation Movement (MPS), on Saturday endorsed Deby's bid for a sixth term as police banned and dispersed protests. Fourteen opposition demonstrators have been held and charged with disturbing public order.
Deby, a 68-year-old former army chief, has been the leader of the central African state since December 1990, when he ousted the autocratic leader Hissene Habre.
He has been re-elected every five years since then, thanks to constitutional changes approved by a referendum in 2005 to remove limits on presidential terms.
During his long rule, Deby has been accused of authoritarianism and nepotism as well as failing to address the poverty that afflicts many of Chad's 13 million people.
Despite oil wealth, the country ranks 187th out of 189 in the UN's Human Development Index (HDI).
Not all of the opposition have so far rallied behind Bongoro.
Romadoumngar Nialbe Felix, whose Union for Renewal and Democracy (URD) has eight seats in the National Assembly and is the biggest single opposition voice in the legislature, was recently named by the party as its candidate in the vote.
Two other prominent leaders who remain outside the Alliance Victoire camp are Laokein Kourayo Medar, who was third in the 2016 elections, and Succes Masra, a young opposition figure who heads a group called The Transformers.
The presidential election will be followed by a legislative ballot, set for October 24. It has been repeatedly postponed since 2015.