Failure of the main Syrian National Coalition to take a clear stance over the talks, which aim to find a political solution to Syria's 2-1/2 year civil war, are also expected to contribute to a delay of up to one month, the officials told Reuters.
"A clearer picture will emerge when the United States and Russia meet next week, but all indications show that the Nov. 23 goal will be difficult to meet," said one of the officials involved in preparing for the talks.
US, Russian and U.N envoys are due to meet in Geneva next Tuesday as part of the preparation for the long-delayed peace conference, which was first proposed back in May.
A main point of contention, the official said, is the role of the Western-backed opposition coalition - an issue which has flared up since a meeting in London last week of Western and Gulf Arab countries opposed to Assad.
They announced that the Geneva negotiations should be between a "single delegation of the Syrian regime and a single delegation of the opposition, of which the Syrian National Coalition should be the heart and lead, as the legitimate representative of the Syrian people."
Russia sees the coalition as just one part of the opposition and has suggested that several delegations, including Damascus-based figures tolerated by the government, could represent President Bashar al-Assad's foes.
That position was echoed by Hassan Abdul Azim, head of the opposition National Coordination Body, who said after meeting international peace envoy Lakhdar Brahimi in Damascus that delegates should attend not under the banner of the coalition but as part of a united "Syrian National Opposition".
A communique at the end of the London meeting also said Geneva would aim to establish a transitional government by which time "Assad and his close associates with blood on their hands will have no role in Syria".
"The Russians are furious at the strong stance taken in London and that the communiqué went a long way towards satisfying the demands of the coalition," a Western official said.
MINISTER SACKED
Preparations for the Geneva talks were thrown into further confusion on Tuesday by the dismissal of Syria's Deputy Prime Minister, Qadri Jamil, after he met senior US diplomat Robert Ford in Geneva on Saturday.
Jamil, a member of what Assad describes as the "patriotic opposition", was sacked for leaving the country without permission and holding unauthorised meetings, state media said.
"He saw Ford after meeting Russian officials in Moscow. The meeting was long but useless," a Middle East official said, asking not to be named.
"Jamil put forward what Ford apparently regarded as unworkable proposals regarding the Geneva talks. He also unsuccessfully tried to win US backing to include him on the opposition side in the Geneva talks," he said.
Another diplomatic source said Russia had backed the idea, but that the coalition would not have agreed to sit on the same side of the table as Jamil in any negotiations.
"It will take time between Russia and the United States to resolve their differences. We are looking now at Geneva between Nov. 23 and Christmas," he said.
Russian Foreign Minister Sergei Lavrov acknowledged the Geneva meeting faced objections from both sides in Syria.
But he added during a visit to Greece: "There are contacts between Russia and the U.S and we should not allow these efforts to fizzle out."
OPPOSITION UNDECIDED
Differences between Moscow and Washington are not the only obstacles to the peace talks going ahead.
Ahmad Jarba, president of the opposition coalition, has publicly resisted calls to commit to attending the so-called Geneva 2 conference, saying the coalition will not take part if there is any chance Assad might cling to power.
"He was speaking to his constituency and his public stance differs from what he told us privately," one delegate at last week's London meeting said, trying to play down the significance of Jarba's stance.
"We assured Jarba that an understanding had been reached with the Russians for Geneva to produce a transitional governing body with full powers over the army and security apparatus and that Assad would not be allowed to retain power under any special clauses. But his fate will not be specifically discussed at Geneva," the delegate said.
Even if Jarba were to attend, he has no authority over the rebel brigades battling to overthrow Assad. Many have rejected any negotiations not centred around Assad's removal and said they would charge anyone who attended them with treason.
Opposition sources said Jarba, who is backed by Saudi Arabia, travelled there in recent days to meet King Abdullah. Jarba will preside over a coalition meeting in Istanbul on Nov. 9 to discuss taking a position on Geneva.
"The meeting will likely stretch for up to a week as usual. What is required is for the coalition to forget rhetoric and come up with a strategy, road map and a detailed policy," one envoy said.
US State Department spokeswoman Jen Psaki said Washington was still planning for a November conference but "no date or details is set or final until the United Nations announces it."
UN Deputy Secretary-General Jan Eliasson told reporters on Wednesday: "We'll continue to work diligently for a conference in Geneva and we're working intensely."
UN spokesman Martin Nesirky added: "We continue to work towards the holding of Geneva 2 and there will be a meeting next week in Geneva to see where those prospects stand and to continue preparations."
Several officials, including Arab League chief Nabil Elaraby, have said they expect the Geneva 2 conference to convene on Nov. 23, though the United States, Russia and the United Nations have all said no date has been officially set.
"A date has not been officially set because no one wants it to be officially postponed," a Western diplomat said. "But it has been clear all along the aim was Nov 23. It looks now that it will be de facto postponed."
