BEIRUT International envoy Lakhdar Brahimi held talks in Damascus on Monday at the end of a Middle East tour to promote a Syrian peace conference, but regional tensions have cast a pall over his mission.
Brahimi visited capitals across the Middle East to discuss plans for the "Geneva 2" meeting, tentatively set for November 23, to try to halt more than 2-1/2 years of bloodshed in Syria.
But opposition forces have not yet decided whether they will attend and Gulf Arab states backing the Syrian rebels have soured on the talks after Brahimi said on Saturday that their rival Iran, Syrian President Bashar al-Assad's main regional ally, should join the international conference.
Brahimi met Syrian Deputy Foreign Minister Faisal Mekdad, in Damascus but there was no word on whether Assad would see him.
A senior Turkish official said the envoy has not pushed for any deal on his tour, remaining in "listening and watching mode" and leaving active negotiating to Moscow and Washington.
Riyadh and Tehran see the struggle in Syria as determining which of them ends up with greater influence in the Arab world.
Saudi Arabia threatened to distance itself from the United States last week over its perceived inaction on Syria and its renewed efforts at reconciliation with Iran.
The diplomatic wrangling has made the Syrian opposition feel weaker and even more reluctant to consider attending Geneva 2.
"All these issues are getting tangled up into the other. Like the Saudis, we are very afraid that the United States' other interests in Iran will come at the cost of the Syrian cause," said Samir Nashar, an executive member of the Syrian National Coalition, the opposition's umbrella body abroad.
"If you ask me, this meeting won't happen on November 23. It won't happen ever."
Syria's political opposition in exile is also facing mounting pressure from fighters on the ground to reject any negotiations that would not require Assad's ouster.
Many of Syria's main rebel brigades on Saturday rejected any negotiations not based on Assad's removal and said they would charge anyone who attended them with treason.
Assad and Iran, however, have said they will only go to talks that set no preconditions.
It is not clear how the United States and Russia, co-sponsors of the talks, can reconcile the conflicting demands of the various parties to enable to conference to convene.
The United States, which backs the opposition, and Russia, a main arms supplier to Assad, agreed in May to try to arrange the Geneva 2 talks to build on an earlier meeting in the Swiss city in June 2012 that called for political transition in Syria, without defining what the Syrian president's role might be.
"The problem is what all the different sides think they're going to get out of Geneva. The opposition and the Gulf see the goal of it as removing Assad. Of course Assad, especially as he's in a position of power right now, won't accept that " said Chris Phillips, a Middle East lecturer at University of London.
Phillips said the United States is now taking a "realist stance" on dealing with Assad, despite its Gulf allies' efforts to draw it into active military support for the rebels.
"We've already seen the West heading in this direction when they began negotiating with Assad to remove Syria's chemical weapons ... Of course most (Western governments) want Assad removed, but the cost of removing him is more than these parties are willing to stomach."
Arab League foreign ministers will meet on Sunday to discuss Syria, officials said. Driven mainly by Gulf countries, the Arab League suspended Syria's membership and has sought to put pressure Assad for trying to crush the uprising against him.
A Gulf diplomatic source in Cairo expressed frustration that Brahimi had not taken a firmer line over the crisis.
"I had hoped that Brahimi would be bold and say there was no solution but for Assad to leave, because Assad's exit from power and his trial along with the pillars of his regime who killed more than 100,000 Syria, is the only solution to the Syrian crisis," said the source, who asked not to be identified.
Some Saudi officials said last week they would now act independently of the United States to arm the rebels - another bad sign for talks that aim to end a civil war that has killed more than 100,000 people, forced millions from their homes and created refugee and security headaches for Syria's neighbours.
Assad's forces have been advancing slowly around the capital Damascus and in parts of central Syria, but overall the conflict remains a violent stalemate that costs at least 100 lives a day.
Despite his relative strength at the moment, Assad has said conditions are not conducive for peace talks, citing Saudi and U.S. support for "terrorists", and arguing that the Syrian National Coalition represents foreign powers, not Syrians.
His opponents are fighting side-battles among themselves, with moderate Islamist groups battling al Qaeda-linked rebel groups in the north, much of which is under opposition control.
Further east, Kurdish militias have seized more territory to consolidate control of a region they want to run independently of both the mostly Sunni Muslim Arab rebels and Assad.
The opposition coalition says it can only attend talks if either the U.N. Security Council, or Washington and Moscow, state publicly that Assad would step down in any transition.
"That would be the encouraging sign we are looking for," said a Syrian opposition source. "Otherwise, when the National Coalition has its planned meeting on November 9, the vote on Geneva is going to be no."
(Additional reporting by Ayman Samir in Cairo; Editing by Alistair Lyon)