LAGOS, Nigeria — Nigeria’s key opposition leaders on Wednesday unveiled a new coalition which they say is aimed at unseating the ruling party in Africa’s biggest democracy ahead of the 2027 presidential elections.

The Africa Democratic Congress coalition, challenging President Bola Tinubu’s All Progressives Congress party, is led by Abubakar Atiku and Peter Obi, both runners-up in the last presidential vote. They are joined by other top figures, including former federal lawmakers and former governors from the ruling party.

“The coalition will stop Nigeria from becoming a one-party state,” said David Mark, a former Senate president and the interim chairman of the alliance, at the unveiling in the capital, Abuja.

Tinubu has been accused of plans to turn Nigeria to a one-party state by allegedly using state mechanisms to convince high-profile politicians to defect from opposition parties to the governing party.

Although the Nigerian leader has denied the allegations, some of his closest allies, including within ruling party leadership, appeared to be supporting it, triggering concerns in a region threatened with shrinking democratic space.

The battle for the country’s top job has intensified, even two years ahead of the next elections, as several federal lawmakers and state governors have defected to the ruling party in recent months, and opposition politicians have coalesced to contest Tinubu’s second term.

The new coalition is reminiscent of the alliance that defeated Nigeria’s former ruling party, the Peoples Democratic Party, in 2015 after an uninterrupted 16-year rule.

As was the case in 2015, many see the current administration as not delivering on their key promises to improve the country’s ailing security and economic sectors.

Tinubu’s government has battled the fallout of unpopular economic reforms after removing decades-long subsidies and floating the country’s currency. The reforms have sparked an inflation crisis as the country deals with a resurgence of attacks by armed groups across the country.

Cheta Nwanze, lead partner at SBM Intelligence, a geo-political consultancy, said only a united opposition bloc stands a chance of unseating Tinubu in 2027.

“You cannot remove a sitting government if the opposition is disunited,” Nwanze said.