Senegalese troops have moved towards the Gambian border in a show of force to pressure President Yahya Jammeh to stand down.
Senegal gave him a midnight GMT deadline to quit as west African states sought UN authorisation to use all necessary means to ensure he does.
Wednesday was meant to be his last day in office but parliament has granted him three more months in the post.
That effectively stops successor Adama Barrow being sworn in on Thursday.
His shock victory in the 1 December election plunged The Gambia into crisis. Mr Barrow is currently in Senegal.
Mr Jammeh has ruled The Gambia since taking power in a bloodless coup in 1994.
At least 26,000 Gambians, fearful that violence could erupt, sought refuge in Senegal this week.
Meanwhile, thousands of UK and Dutch tourists are being evacuated from the tiny West African state, which is popular with European holidaymakers because of its beaches.