Russia and other big powers have agreed to back a proposal by UN envoy Kofi Annan for a national unity government to lead political change in Syria.
Western diplomats say the proposed cabinet could include members of the opposition and government, but no-one who would undermine its credibility.
While they see President Bashar al-Assad as excluded from the plan, it is not clear if Russia shares that view.
The idea will be discussed on Saturday by the UN Action Group on Syria.
According to an unnamed diplomat quoted by Reuters, Mr Annan made clear that any settlement should also be irreversible, with clear transition steps and a fixed timeline.
"These include establishing a transitional national unity government to create a neutral backdrop for transition," the diplomat said.
"It could comprise present government members, opposition and others, but would need to exclude those whose continued participation or presence would jeopardise the transition's credibility, or harm prospects for reconciliation and stability."
The BBC's Barbara Plett, in New York, says that the implication is that Mr Assad would not form part of the government, although this has not been made explicit.
Russia has resisted pressure to remove President Assad, saying that his future should be left to the Syrian people alone, and not imposed by outside powers.
Earlier this month, President Vladimir Putin poured cold water on the idea that removing the current leadership would bring about "general wellbeing".W
But BBC Moscow correspondent Steve Rosenberg says that if Russia concludes that if Mr Assad has become a liability and that its national interest would be best served by a government without him, then it would be the first to sign up to that.
In April, following months of bloodshed, the Syrian government agreed to a six-point peace plan.
UN monitors were deployed to oversee a ceasefire but the truce never took hold and the monitors have suspended patrols.
US Secretary of State Hillary Clinton, who will attend Saturday's meeting, said that if all the parties agreed to Mr Annan's roadmap for political transition then there was "great hope that this perhaps can be a turning point in the very tragic circumstances affecting the Syrian people".
The proposal will be discussed in Geneva by the five permanent members of the Security Council as well as regional powers Turkey, Iraq, Kuwait and Qatar.
Russia's UN ambassador Vitaly Churkin said Moscow was "looking forward to intensive interaction among the foreign ministers" to push for an end to fighting and a start to political talks.
Our correspondent says that a political transition plan cannot be implemented as long as the violence continues.
On Wednesday, at least seven people were killed during an attack on pro-regime satellite channel al-Ikhbariya TV south of Damascus.
Violence was also reported by opposition activists in the central city of Homs, Deir al-Zour in the east and in Idlib in the north.
Clashes in suburbs of Damascus on Tuesday were described by activists as the worst there so far.
President Assad has described his country as in a "real state of war from all angles" and, on Wednesday, Mr Annan's deputy envoy, Jean-Marie Guehenno, said that the violence "had reached or even surpassed" the levels seen in April when the ceasefire plan was agreed.
The UN says at least 10,000 people have been killed since pro-democracy protests began in March 2011. In June, the Syrian government reported that 6,947 Syrians had died, including at least 3,211 civilians and 2,566 security forces personnel.