Ahmad Jarba, the president of the opposition Syrian National Coalition, says he believes the world now agrees that President Bashar al-Assad must leave power.
International efforts to get the two Syrian delegations to talk will continue in Swiss city of Geneva on Friday after two days of indirect discussions.
It is thought there will be an attempt to broker ceasefires and obtain better access for aid workers.
Al Jazeera's Zeina Khodr reports from Geneva.