Nigeria's president is leading a regional delegation to Gambia in a last-ditch attempt to persuade its longtime leader to step down and allow his rival's inauguration next week.

President Muhammadu Buhari has been authorized to offer Gambian President Yahya Jammeh asylum, if necessary, during Friday's visit.

The West African regional bloc also has a military force on standby to intervene if Jammeh does not step down when his mandate expires Jan. 19.

Jammeh at first accepted his Dec. 1 election loss but changed his mind. His party has contested the results in court.

Fears are growing that the impasse will turn violent.

President-elect Adama Barrow is renewing his offer to Jammeh for direct discussions on the crisis, telling the BBC that "I'll be very willing to talk to him directly."