Western and Arab diplomats are seeking a UN Security Council resolution calling for Syrian president Bashar al-Assad to go as his forces take the upper hand in battles on the outskirts of the capital Damascus.
The Arab League wants the Security Council to pass a resolution backing an Arab peace plan that calls on Dr Assad to relinquish power to his deputy and prepare for elections.
Its Secretary-General Nabil Elaraby and the prime minister of Qatar will make the case at the world body later today.
The Arab delegation will be supported in person by US secretary of state Hillary Clinton, British foreign secretary William Hague and French foreign minister Alain Juppe as the West presents a united front.
The resolution's fate depends on whether the Arabs and their Western backers can persuade Russia not to veto it, however.
UN Secretary-General Ban Ki-moon said today he hoped the Security Council would reflect international will to get Dr Assad to quit power.
"I sincerely hope the Security Council will be united and speak in a coherent manner reflecting the wishes of the international community," he told reporters in the Jordanian capital. "This is crucially important."
In Syria, rebels who seized suburbs of Damascus were driven out after three days of fighting that activists say killed at least 100 people.
Activist organisations said 25 people were killed yesterday in Damascus suburbs and dozens more died in other parts of the country, mostly in raids in Homs and the surrounding countryside.
Events on the ground are difficult to confirm, as the Syrian government restricts most access by journalists.
A 10-month uprising against Dr Assad - one of the most violent revolts of the "Arab Spring" - has entered a new phase in recent weeks, with an increasingly armed and organised opposition attempting to hold territory.
A last-ditch bid by Moscow to broker talks between Dr Assad's government and rebels foundered when the opposition refused to attend, citing the continued killing, torture and imprisonment of the president's opponents.
A senior Russian diplomat said today the push for adoption of a Western-Arab draft UN Security Council resolution on Syria was a "path to civil war," the Interfax news agency reported.
"The Western draft Security Council resolution on Syria will not lead to a search for compromise," Interfax quoted Deputy Foreign Minister Gennady Gatilov as saying. "Pushing it is a path to civil war."
However, Washington said countries needed to accept that Dr Assad's rule was doomed and stop shielding him in the Security Council.
"It is important that the Security Council take action," White House spokesman Jay Carney said yesterday. "We believe that the Security Council should not permit the Assad regime to assault the Syrian people while it rejects the Arab League's proposal for a political solution."
"As governments make decisions about where they stand on this issue and what further steps need to be taken with regards to the brutality of the Assad regime, it is important to calculate into your considerations the fact that he will go," Mr Carney said. "The regime has lost control of the country and will eventually fall."
Syria was dismissive of the US remarks.
"We are not surprised at the lack of wisdom or rationality of these statements and regret that they are still issued by countries that are used to making the Middle East an arena for their follies and failures," the state news agency quoted a Foreign Ministry source as saying late yesterday.
A draft of the UN Security Council resolution, obtained by Reuters, calls for a "political transition" in Syria, and says the Security Council could adopt unspecified "further measures" if Syria does not comply with its terms.
It endorses the Arab League power transfer plan. So far Moscow has shown little sign of being persuaded to let it pass.
"The current Western draft is only a step away from the October version and can by no means be supported by us," Russian Deputy Foreign Minister Gennady Gatilov told Interfax. "This document is not balanced . . . and above all leaves the door open for intervention in Syrian (internal) affairs."
Nevertheless, some Western diplomats said they hoped Russia and China could be persuaded not to block the draft.
An abstention by Russia and China last March paved the way for the Security Council to authorise force against Muammar Gaddafi's military in Libya with Arab League support.
Making the Arab League's case, Mr Elaraby will be joined by Qatari Prime Minister Sheikh Hamad bin Jassim al-Thani, whose country heads the League's committee dealing with Syria.
Reuters