Jammeh's party has vowed to challenge the December 1 vote result in court, leading to an avalanche of international condemnation and multitude of calls for him to cede power to opponent Adama Barrow, who was officially declared the winner.
Jammeh is expected to meet Nigeria's Muhammadu Buhari, Liberian leader Ellen Johnson Sirleaf, Sierra Leone's Ernest Bai Koroma and Ghana's outgoing President John Mahama this morning.
The heavyweight delegation of west Africa's biggest hitters, who have significant ties to The Gambia, will be joined by United Nations West Africa envoy Mohamed Ibn Chambas.
Banjul-based diplomats say Buhari in particular has long been annoyed by Jammeh's provocative behaviour and disdain for protocol.
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Up until now the president of the tiny country of fewer than two million people may have exasperated his peers but has never threatened peace in the sub-region, a situation that has dramatically shifted since Jammeh's move to void the election.
"It is unacceptable that there is an election and one person turns down the result," Liberia's information minister Eugene Nagbe told AFP today. "The message of President Sirleaf and her delegation to Jammeh will be that he accepts the result and gives way to smooth transition."
Streets from the airport were quiet as Gambians awaited the leaders' arrival, but some parents kept their children home from school as a precaution.
President-elect Barrow has told AFP he wants Jammeh to step down "now", though the longtime leader has the legal right to stay in office until mid-January.
The African Union has also promised to dispatch its own delegation as soon as possible to aid the transfer of power, while a statement released Monday said it rejected "any attempt to circumvent or reverse the outcome of the presidential election.