Russia wants the Syrian government and opposition to agree on launching a constitutional reform process of up to 18 months, followed by early presidential elections, a draft document obtained by Reuters showed on Tuesday.
The eight-point proposal, drawn up by Moscow before multi-lateral talks on Syria this week, does not rule out President Bashar al-Assad's participation in the early elections, something his foes say is impossible if there is to be peace.
"(The) popularly elected president of Syria will have the functions of commander-in-chief of the armed forces, control of special services and foreign policy," the document said.
The proposal said the Syrian sides should agree on such steps at a future conference organised by the United Nations and added that the reform process would not be chaired by Assad, but by a candidate agreed by all sides.
Russia and Iran have been Assad's top allies during Syria's nearly five-year war. The United States, its Gulf allies and Turkey have said he must leave power for there to be peace.
After initially dismissing Syrian opposition groups fighting Assad, Moscow has stepped up diplomatic efforts to resolve the conflict that has killed some 250,000 and displaced millions.
At a first round of peace talks in Vienna late last month, where Russia was a leading player, Moscow said it wanted opposition groups to participate in future discussions on the Syria crisis and exchanged a list of 38 names with Saudi Arabia.
The document said the Syrian opposition which takes part in the political process must form a "united delegation" and be agreed beforehand.
"(They should) share the goals of preventing terrorists from coming to power in Syria and of ensuring sovereignty, territorial integrity and political independence of Syria, as well as (the) secular and democratic character of the state."
Western diplomats said it would be difficult for countries opposed to Assad to agree on the draft Russian proposal.
"The document does not suit a lot of people," one Western diplomat said, adding that those who disagreed with Russia's approach were working to make sure the text would not be the basis of the talks.
The document also proposed agreeing on a list of terrorist groups. Russian Foreign Minister Sergei Lavrov said earlier on Tuesday that Moscow wanted to see such an agreement at the Vienna talks.
The text also said that for a Syrian ceasefire, "operations against ISIL (Islamic State) and other terrorist groups must be excluded".
A second Western diplomat said Moscow wanted to use this definition to cover all insurgent groups, not just jihadists such as Islamic State and al Qaeda's Nusra Front. "Russia wants this list to include all the groups that fight anything else except Islamic State, so that means groups against the regime," the diplomat said.