CAR crisis: Djotodia's future hangs in the balance
Central African Republic (CAR) interim President Michel Djotodia is expected to face pressure to step down when he attends a regional summit on Thursday.
His failure to quell violence between Christian and Muslim militias has prompted speculation that he may quit.
However, CAR officials say his resignation is not on the agenda at the CEEAC summit in neighbouring Chad.
Seleka rebels staged a coup last March, installing Mr Djotodia as the country's first Muslim president.
The then-President Francois Bozize, from CAR's majority Christian population, was forced into exile and the country has since descended into chaos.
The UN has warned of an impending humanitarian disaster.
Ahmat Allami, Secretary General of CEEAC (Economic Community of Central African States) said the group would tell Mr Djotodia that his transitional government was not working.
"If you are incapable, if you are powerless in the face of the situation, make way for others who can do a better job," Mr Allami said in the Chadian capital N'Djamena.
"It may happen that CEEAC... cannot continue to support the transition."
However, he added that "regime change" was not the goal of the meeting.
A source close to Mr Djotodia quoted by Reuters said that CAR leaders had run out of patience with him.
"It's finished for him now," said the source.
French officials also quoted by Reuters said the summit would discuss various options for continuing the transition, including allowing the president of a National Transitional Council to take over or mandating Prime Minister Nicolas Tiangaye to run the country until elections.
Although Mr Djotodia has officially disbanded the Seleka rebels, he has proved unable to keep them in check.
Their brutal actions have prompted Christians to form vigilante groups, sparking a deadly cycle of revenge attacks.
More than 1,000 people have died in the past month alone and the number displaced has more than doubled, to nearly a million.
On Wednesday, the UN warned that measles had broken out at the airport in the capital, Bangui, where about 100,000 people are seeking refuge from clashes.
France has deployed 1,600 troops to try to end the violence and the African Union also has some 4,000 peacekeepers in the country.
The UN says about half the population of Bangui - more than 500,000 people - have been driven from their homes and 2.2 million people are in need of humanitarian assistance.