Russian Foreign Minister Sergei Lavrov says arranging a Syria peace conference has been a "tall order."
Lavrov spoke on May 27 after talks on the Syrian crisis with U.S. Secretary of State John Kerry in Paris.
The United States and Russia have launched a joint initiative to bring together Syria’s fractious opposition forces and the government for an internationally-backed peace conference in June in Geneva.
However, the date and participants of such a conference have not yet been set.
"It's not an easy task. It's a very tall order," Lavrov said. "But I hope that when the United States and the Russian Federation take this kind of initiative, the chances for success are there. We will do everything in our power to use those chances, and to make them realized."
The government of President Bashar al-Assad has said it is ready to attend the conference.
But the opposition, riven by factional disputes, continues to struggle to agree on a unified position and has not yet committed to attend.
The opposition has said previously it will not negotiate without Assad’s regime first agreeing to leave power.
Another point of contention has been the participation of Iran, a leading ally of the Syrian regime, in any conference.
Russia has backed Iranian participation. But this is opposed most vocally by France, a leading Western backer of the rebels.
In his remarks on May 27, Kerry said Washington and Moscow remained committed to the Geneva Communique, an international statement agreed on last year that calls for formation of a transitional Syrian government that would be chosen by opposition groups and Assad’s government.
Kerry also said Washington and Moscow remain concerned about the possible use of chemical weapons in Syria.
"Both of us expressed our mutual concerns about any potential use of chemical weapons, and the need to really get the evidence and ascertain what has happened in that regard," Kerry said. "Both Russia and the United States, if it [chemical weaponry] were being used, object to that very very strongly."
Both the Syrian government and opposition have accused each other of using chemical weapons during the conflict, which is now in its third year.
In related development, the European Union has announced it is ending its embargo on weapons supplies to the Syrian rebels.
Officials said, however, that no decision has been made yet by any EU country to begin providing arms to the opposition.
While the arms embargo is being lifted, the EU said it will maintain financial and economic sanctions targeting the Syrian government over its failure to bring the conflict to an end.
Based on reporting by Reuters, AP, AFP, and dpa