The Peoples Democratic Party (PDP), and four other political parties on Thursday agreed to work together to unseat the All Progressives Congress in 2019.
They included the Peoples Democratic Party, Peoples Redemption Party, Social Democratic Party, Alliance for Democracy and Accord Party.
A former minister, Prof Jerry Ghana reportedly led the PDP delegation to the meeting.
Gana had disclosed on Wednesday that the PDP was planning to team up with other parties.
The parties in a communique on Thursday said they were attempting to save the country.
They said the Buhari administration has messed up the economy and scared away investors.