The plan, unveiled by world powers at an international conference in Geneva in June, called for an open-ended cease-fire, a transitional government to run the country until elections, and the drafting of a new constitution. The plan was a non-starter for the opposition because it did not explicitly ban authoritarian President Bashar Assad and other members of his regime from taking part in the transitional leadership.
The regime ignored it because it would entail voluntarily giving up power.
There was no sign that the plan had any more chance of succeeding now than it did back in June. Assad's government did not comment on the attempt to revive the proposal, and a coordinator for the rebels seeking to end Assad's rule called the plan "illogical."
"No one in the opposition can accept this, and if they accept it, it will be refused by the Syrian people," said Bassam Al-Dada, a Turkey-based coordinator with the rebel Free Syrian Army. He said Assad's forces have killed too many people for him to play a role in any solution.
Anti-regime activists say more than 40,000 people have been killed since the revolt against Assad began in March 2011.
Because of Russian objections, the original plan did not call specifically for Assad's ouster nor ban him or top members of his regime from participating in the new government.
Much has changed in Syria since the plan was first presented. Rebels have gained momentum, seizing more territory and a number of military installations in the country's north. They are also expanding their control in suburbs of the capital, Damascus.
These gains make it increasingly unlikely that they will accept any plan that allows any part of Assad's regime to remain.
The government, too, has given no indication it will give any ground and dismisses almost all opposition activities as terrorism that seeks to destroy the country.
In Damascus on Thursday, the U.N. envoy for Syria Lakhdar Brahimi called the Geneva plan "suitable enough" to end Syria's war.
"The Syrian people seek genuine change," Brahimi said, adding that the transitional period "must not lead to the collapse of the state or the state's institutions."
Brahimi said that original plan could be amended, but he didn't say how.
He did not mention Assad by name and only said the transitional government would have "full executive powers," meaning "all the authority of the state should be possessed by that government."
Brahimi said it remained to be determined what kind of government would follow and whether the elections called for under the plan would be for president or parliament.
In Moscow, Foreign Ministry spokesman Alexander Lukashevic said Russia, too, is trying to revive the Geneva plan.
"We continue to believe that there is no alternative to that document in trying to find a settlement in Syria," Lukashevich said.
He also reaffirmed Moscow's objection to calls for Assad's ouster.
Russia has been Assad's strongest backer throughout the conflict, selling arms to his forces and, along with China, protecting him from censure by the U.N. Security Council for his violent crackdown on the opposition.
Top Russian officials have recently signaled a new resignation to the idea that Assad could fall. Still, they have said they will not call for his ouster or offer him refuge should he decide to flee.
Brahimi is expected to visit Russia this weekend. Syrian Deputy Foreign Minister Faisal Mekdad met Thursday with Russia's Foreign Minister Sergey Lavrov to pave the way for Brahimi's visit.
Mekdad is expected to hold talks with other top Russian diplomats later.
Violence flared in Syria again on Thursday, with rebels attacking a police academy and military airport in the northern province of Aleppo while clashing with government forces near the Wadi Deif military base in northern Idlib province.
The Britain-based Syrian Observatory for Human Rights said 11 rebels and 16 government soldiers were killed in clashes around Idlib province.
A car bomb blew up in the Damascus suburb of Sbeineh, killing four people and wounding ten, the state news agency reported.
Associated Press writers Albert Aji in Damascus, Syria, and Vladimir Isachenkov Moscow contributed reporting.