"We were hoping that we would be in a position to announce a date today; unfortunately we are not," said U.N.-Arab League envoy Lakhdar Brahimi, who chaired the meeting at the United Nations in Geneva. "But we are still striving to see if we can have the conference before the end of the year."
Brahimi conferred with senior U.S. and Russian officials before widening the talks to include representatives from Britain, France and China, as well as Syria's neighbors Iraq, Jordan, Lebanon and Turkey, and the Arab League.
"The opposition has a very, very difficult time," he said. "They are divided. It is no secret for anybody. They are facing all types of problems and they are not ready."
Russian Deputy Foreign Minister Gennady Gatilov, who met Brahimi along with fellow Deputy Foreign Minister Mikhail Bogdanov, said the United States, which has backed the revolt against Assad, did not have the leverage needed to assemble a credible opposition delegation representing various factions.
"It is not just the representation of the opposition that is required, but the participation of an opposition delegation of a broad range of opposition forces. And this is what the Americans are failing to achieve," RIA news agency quoted him as saying.
The proposed peace conference is meant to build on a June 2012 agreement among world powers in Geneva that called for a transitional authority with full executive powers, but did not explicitly say Assad should step down.
Damascus reiterated on Monday that Assad would stay in power come what may, casting doubt on the political transition that is the main focus of the proposed "Geneva 2" conference.