The US blamed Russian Federation, which proposed an amendment to delay it.
UN Special Envoy for Syria Staffan de Mistura has called again for an urgent ceasefire to relieve the "appalling suffering" of Syrian civilians by stopping the bombing there and the "indiscriminate" mortar shelling of Syria's capital Damascus.
The Security Council's 15 members were unable to reach an agreement on draft text and delayed the vote three times on Friday before putting it off for yet another day. Let s do this tonight.
State Department Spokesperson Heather Nauert told a separate news conference that more than 400 civilians were "horrifically" killed by the Syrian regime. They have said their main aim is to stop rebel shelling of the capital, and have accused insurgents in Ghouta of holding residents as human shields.
The Syrian Observatory for Human Rights said that "five days of air strikes and intense artillery fire by the regime and its Russian ally have killed 403 civilians, including 95 children".
Russia's U.N. Ambassador Vassily Nebenzia has called an immediate cease-fire unrealistic and proposed an amendment to delay it.
"We are still working on language on some of the paragraphs, but we are nearly there", council president Kuwaiti Ambassador Mansour al-Otaibi told reporters mid-day Friday. Protesters have been long demanding the resignation of Syrian President Bashar al-Assad over his autocratic rule.
A previous draft had said the ceasefire would go into force 72 hours after the adoption, but that was dropped from the text in a bid to reach compromise with Russian Federation.More news: Florida shooting survivor: Trump Jr. is 'immature, rude, and inhuman'
The initial resolution called for the ceasefire to begin 72 hours after its adoption, but diplomats continued discussions into the night about the final wording. "That's what we're working on".
The proposal was for a vote at midday EST (5pm United Kingdom time).
"It is about saving lives", Sweden's Skoog said earlier.
"UN convoys and evacuation teams are ready to go".
On Thursday, the Syrian helicopters dropped leaflets over Eastern Ghouta, urging the civilians to leave the area and not to cooperate with the rebels.
Yassin was hit by shrapnel from a barrel bomb en route to a hospital where he had planned to report on the effects of Assad-aligned forces' airstrikes on Hammouriyeh, according to Abdulmonam Eassa, a freelance photographer for Agence France-Press (AFP) and the Hammouriyeh and Ghouta Media Centers.
Syrian state TV reported that militants fired 70 shells at Damascus, with one person killed and 60 others wounded.
U.S. Ambassador Nikki Haley, who did not participate in Friday's negotiations, tweeted: "Unbelievable that Russian Federation is stalling a vote on a ceasefire allowing humanitarian access in Syria".