The UN General Assembly is due to vote on a resolution that condemns the Syrian government's use of "heavy weapons" and its failure to withdraw forces from civilian areas.
The text was expected to easily pass in the 193-member General Assembly on August 3 after its Arab sponsors removed two provisions in the original draft -- a call for nations to place sanctions on Syria and a demand that President Bashar al-Assad resign.
The resolution requires a simple majority of the assembly to pass. It is not legally binding but is intended to increase pressure on the Security Council to take action.
The vote is overshadowed by the resignation of UN-Arab League envoy Kofi Annan, who said growing militarization had made his job untenable.
Announcing his decision on August 2, Annan also criticized the Security Council, which he said had prevented any consensus on action.
"At a time when we need -- when the Syrian people desperately need action, there continues to be finger-pointing and name-calling in the Security Council," Annan said.
Russia and China, in particular, have come under fire for blocking UN attempts to impose sanctions against Damascus.
In the wake of Annan's announcement, several nations moved to consolidate their roles in seeking a resolution to the conflict.
Russian news agencies reported that three Russian naval vessels with marines on board were on route to the Syrian port at Tartus and would arrive there early next week.
British Foreign Secretary William Hague said his country would increase what he called "nonlethal support" to rebel groups in Syria.
UN 'Failure' In Syria
Annan's departure sparked further criticism of the Security Council from rights groups alarmed by the bloodshed in Syria.
Syrian opposition activists say around 18,000 people have been killed since the uprising against Assad began in March 2011.
Suzanne Nossel, executive director of Amnesty International in the United States, spoke scathingly about the UN's handling of the Syrian crisis.
"Even as seasoned diplomat as Kofi Annan is almost throwing up his hands and really putting the responsibility I think where it belongs," she said, "on the Assad government and on leading world governments who come together in the Security Council and have an obligation to address this crisis, but have failed to do so."
On August 3, Iran, which has voiced strong support for Annan's plan, blamed "some interfering countries" for the UN stalemate.
Iran's Foreign Ministry said these countries were "not happy" with Annan's attempt to stop the shipment of arms to Syria.
Iranian Foreign Minister Ali Akbar Salehi charged that the West and several regional countries "did not want Annan to succeed."
Annan's six-point peace plan for Syria was never fully adhered to by either side of the Syrian conflict.
The plan centered on an April cease-fire that never took hold.
On August 3, activists reported further deaths across the country, including in Syria's biggest city, Aleppo, where pro-government forces are trying to reclaim areas seized by rebels.
UN peacekeeping chief Herve Ladsous, meanwhile, told the Security Council that UN military observers in Aleppo were seeing "a considerable buildup of military means, where we have reason to believe that the main battle is about to start."
UN Secretary-General Ban Ki-moon has urged all sides to show restraint and refrain from "ever-increasing violence."
With reporting by Reuters, AP, and AFP