Nigerian politician Peter Obi said he would run for president again in January after winning his party's nomination, setting up another contest between incumbent Bola Tinubu ​and a divided opposition.

Obi was declared the winner of the Nigeria Democratic Congress ‌primary on Sunday, less than a month after quitting an alliance that had tried to set up a single opposition challenger.

The acceptance from Obi, who came third in the last election after galvanizing ​young voters, hit hopes among some opposition backers that he might return to ​the coalition.

It prepares the ground for a re-run of 2023's three-way contest ⁠that is likely to test whether public anger over rising living costs and insecurity ​can translate into votes against Tinubu, or whether the anti-government vote will once again be ​split.

"We must address insecurity with resolve and urgency, for no nation can thrive while its citizens live in trepidation," Obi said in a statement late on Sunday.

Nigeria is grappling with overlapping security crises ​that stretch far beyond the jihadist insurgency in the northeast, where Boko Haram and ​Islamic State West Africa Province have waged a conflict for more than 15 years.

In the northwest, heavily ‌armed ⁠gangs known locally as bandits carry out mass kidnappings for ransom and raids on villages and schools, while north-central states have also seen recurring violence linked to disputes over land and grazing routes.

Voters will also be focused on Tinubu's economic reforms, including the ​removal of fuel and ​electricity subsidies and ending ⁠currency controls, which have won over investors even as Nigerians watch their incomes and savings erode.

Higher global oil prices linked to ​the Iran conflict have added to the pressure, with Nigeria experiencing ​some of ⁠the steepest fuel price increases among major African economies.

Tinubu on Friday defended his reforms, saying they had stabilised the country and revived investor confidence, despite the squeeze on households.

Former Vice President ⁠Atiku ​Abubakar, runner-up in the last election, last week won ​the ticket to represent the African Democratic Congress party, in what will be his seventh presidential bid.

Leaders of ​other smaller parties are also expected to run.