Leaders from the Economic Community of West African States (ECOWAS) have announced a plan to visit Gambia for a second time in less than a month in an effort to persuade the country’s longtime ruler to hand over power to the president-elect.

Nigerian officials said Monday that President Muhammadu Buhari will lead three West African heads of state to Gambia on Wednesday in the second such trip to the country after the disputed presidential election of December 1, 2016.

Nigerian Foreign Minister Geoffrey Onyema said Buhari had agreed on the mission in a meeting with presidents of Liberia and Senegal earlier in the day. The agreement comes two days after ECOWAS leaders met in Ghana to reiterate their call for a diplomatic solution to the crisis in Gambia.

Gambia’s Jammeh had initially admitted defeat in the votes but later changed his mind and challenged the results of a recount.

The long-time leader refused an initial plea by ECOWAS leaders to cede power, prompting the regional bloc to threaten him with the use of military force.

Jammeh’s mandate expires on January 19, when Gambia is to inaugurate President-elect Adama Barrow. The former real estate agent defeated Jammeh by a marginal difference in the votes.

Jammeh has censured the ECOWAS warning about a military intervention as a "declaration of war."

In a New Year speech, Jammeh also accused the African leaders of trying to undermine the sovereignty of Gambia.