The UN special envoy to Syria is travelling to Damascus to try to reduce the fighting which has intensified in Aleppo, where rebels claim to have killed 300 government soldiers in the past week.
Staffan de Mistura, who is on his fourth trip to the country since July and is expected to arrive in the capital on Monday, says he has received some assurances from the government that it will stop its aerial bombardment of Aleppo for six weeks.
Mistura has not yet received agreement from opposition groups and in a recent interview with Al Jazeera's Diplomatic Editor James Bays said he knew many believed the odds were against the success of his initiative.
He is expected to travel to Istanbul following his visit to Syria to talk to opposition groups.
"My chances, I hope are not super slim, because that would in a way would also reflect the chances of the Syrian people to see hope at the end of this tunnel," Mistura said.