Chad President Idriss Deby has taken a strong early lead and appeared poised to extend his three-decade rule, partial provisional results of the April 11 presidential election released by the election commission showed.

Deby has won a majority in all but one of the 51 departments announced so far, and secured a plurality in the other, with 61 departments remaining, according to the Independent National Election Commission (CENI).

On Saturday Kilmapone Larme, head of logistics at the CENI, said they had still not received more than 30% of results.

An ally of Western powers in the fight against Islamist militants in West and Central Africa, Deby is one of Africa’s longest-serving leaders, but there are signs of growing discontent over his handling of the nation’s oil wealth.

Chad’s government has been forced to cut back public spending in recent years because of the low price of oil, its main export, sparking labour strikes.

Opposition leaders called on their supporters to boycott the polls and make the country “ungovernable” after Deby’s decision to seek a sixth term led to protests and clashes with security forces.

Deby has relied on a firm grip over state institutions and one of the region’s most capable militaries to maintain power.

On April 9 authorities said they had arrested several people, including at least one opposition leader, for what they said was a plot to assassinate politicians and bomb polling stations and the electoral commission headquarters.