(REUTERS) -- Syrian President Bashar al-Assad's forces have taken the upper hand in escalating battles on the outskirts of the capital Damascus while top Western and Arab diplomats are seeking a U.N. Security Council resolution calling for him to go.
Rebels who seized suburbs of Damascus were driven out after three days of fighting that activists say killed at least 100 people.
Activist organizations said 25 people were killed on Monday 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.
The Arab League wants the Security Council to pass a resolution backing an Arab peace plan that calls on 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 on Tuesday.
The Arab delegation will be supported in person by 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.
A 10-month uprising against Assad - one of the most violent revolts of the Arab Spring - has entered a new phase in recent weeks, with an increasingly armed and organized opposition attempting to hold territory.
A last-ditch bid by Moscow to broker talks between Assad's government and rebels foundered when the opposition refused to attend, citing the continued killing, torture and imprisonment of the president's opponents.
Washington said countries needed to accept that 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 on Monday. 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, Carney said. The regime has lost control of the country and will eventually fall.
Syria was dismissive of the U.S. 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 on Monday.
A draft of the U.N. 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 authorize force against Muammar Gaddafi's military in Libya with Arab League support.
Making the Arab League's case, Elaraby will be joined by Qatari Prime Minister Sheikh Hamad bin Jassim al-Thani, whose country heads the League's committee dealing with Syria.
ASSAULT ON DAMASCUS BEATEN BACK
Assad's forces appear to have decisively beaten back an attempt by the opposition to march on the outskirts of Damascus.
Activists and residents said Syrian troops now had control of Hamouriyeh, one of several districts where they have used armored vehicles and artillery to push back rebels who came as close as 8 km (5 miles) to Damascus.
An activist said the Free Syrian Army (FSA) - a force of military defectors with links to Syria's divided opposition - mounted scattered attacks on government troops who advanced through the district of Saqba, held by rebels just days ago.
Rebels are risking heavier clashes and speaking of creating liberated territories to force diplomatic action. In the past three weeks they have taken Zabadani - a town of 40,000 in mountainous near the border with Lebanon.
God willing, we will liberate more territory, because the international community has only offered delayed action and empty threats, said a lieutenant colonel who had defected to the FSA and asked not to be identified.
Homs residents said fighting erupted on Monday in the al-Qusour neighborhood, and several armored vehicles belonging to loyalist forces where destroyed.
In the northern commercial hub of Aleppo, which had remained mostly on the sidelines in the uprising as an alliance between Assad and the city's Sunni Muslim merchant class held, demonstrations erupted for a fourth day in several districts.
Tension rose there after pro-Assad militiamen killed 10 people following a pro-democracy demonstration on Friday.
Security forces cut off electricity from Fardos neighborhood of Aleppo and arrested 100 youths on Monday after a demonstration demanding the removal of Assad, activists said.
Syria's state news agency said six soldiers died in an attack near Deraa in the south and a gas pipeline was blown up.
The state news agency SANA has reported funerals of more than 70 members of the security forces members since Friday.
Russia's Foreign Ministry said Syria agreed to Russian-brokered negotiations over the crisis, but senior members of the council set up to speak for a fragmented Syria opposition said there was no point in talking to Assad, who must quit.
We rejected the Russian proposal because they wanted us to talk with the regime while it continues the killings, the torture, the imprisonment, Walid al-Bunni, foreign affairs chief for the Syrian National Council, told Reuters.
The escalating bloodshed prompted the Arab League to suspend the work of its monitors on Saturday. Arab foreign ministers, who have urged Assad to step down and make way for a government of national unity, are due to discuss the crisis on February 5.
The United Nations said in December more than 5,000 people had been killed in the protests and crackdown. Syria says more than 2,000 security force members have been killed by militants.