Former Gambian foreign minister Sidath Diop has told the BBC that Mr Jammeh has defied West African leaders because he believes his army will fight for him.
However Mr Jammeh commands little loyalty in the armed forces, Mr Diop said.
Mr Jammeh believes he “owns The Gambia” and does not know how to respond to the looming end of his reign, the former minister said.
“It is the sky that has fallen on him and he doesn’t know how to go away. People understand this and they are giving him a lot of chances,” he said.
The latest ultimatum is for him to give up by noon or face removal by force.