Syrian opposition groups meeting in Doha agreed in principle on Sunday on a plan to unite against President Bashar al-Assad following marathon talks and pressure from international backers.
The putative deal is based on an initiative that envisages the formation of a transitional government, a military council to oversee rebel groups on the ground and a judiciary to operate in rebel-held areas.
It came as forces loyal to President Assad suffered a fresh blow, with two suicide car bombings tearing through an officers' club in the southern city of Daraa, cradle of the nearly 20-month uprising.
"We have agreed on the main points of the formation of a Syrian national coalition for the forces of the opposition and the revolution. We will continue our discussions on the details on Sunday," opposition figure Suhair Atassi told AFP early Sunday after 12 hours of talks in Doha.
"We were on the point of signing (the accord) but we preferred to give some time to study the internal rules at the request of certain parties," said fellow delegate Riad Seif, reportedly seen by Washington as a potential new opposition chief.
The participants were set to resume their talks at 0700 GMT.
In Damascus, Syria's Information Minister Omran al-Zohbi called Saturday for a national dialogue and said the army was fighting to boost the chance for talks.
"The only way to succeed in Syria is to sit down at the table to launch a national dialogue," Zohbi said. "The opposition must accept the choice of dialogue and... the army, by facing down terrorism, is protecting this dialogue."
Saturday's attacks killed 20 soldiers and possibly many more, said the Syrian Observatory for Human Rights.
"The two bombings were the result of suicide attacks, carried out by two men who drove vehicles loaded with explosives into the garden a few minutes apart," Observatory director Rami Abdel Rahman said.
State news agency SANA reported that three car bombings killed seven people and wounded many, but did not say they were at a military position.
It also said a car bomb had wounded nine people in the southern Damascus neighbourhood of Daf al-Shawk, while state television said a rocket wounded two girls in the capital's Christian district of George Khoury.
Elsewhere, the army retook a stretch of the Damascus-Aleppo highway used to send its reinforcements to main northern battlefields, said the Observatory.
Regime forces had "gradually advanced over the past 10 days to regain control of several villages that fell in (early) October to the rebels to the west of the Damascus-Aleppo highway," Abdel Rahman told AFP.
But the army had so far failed to enter the strategic rebel-held town of Maaret al-Numan, where fighting intensified after soldiers in the besieged nearby military base of Wadi Deif received supplies.
News of a potential deal among the disparate Syrian opposition groups came with the Syrian National Council (SNC) under increased Arab and Western pressure to accept a unity plan, amid growing frustration among other dissident groups.
Once regarded as the leading opposition representative but increasingly derided in Washington as dominated by out-of-touch exiles, the SNC had already twice asked for a postponement of the talks on plans for a broad-based government-in-waiting.
The plan, which is based on an initiative by Seif, would see a 10-member transitional government elected by a new 60-member umbrella group drawn from civilian activists and rebel fighters inside Syria, as well as by the exiles who have dominated the SNC.
On Saturday the SNC had put forward its own proposals and its new leader George Sabra told reporters in Doha that "the SNC is older than... any other initiative" on the table, adding that no opposition group should be forced under the banner of another.
Another senior SNC official Ahmad Ramadan said: "We are being submitted to pressure to accept being part of a new formation, in exchange for international promises but with no guarantees."
According to watchdog the Syrian Observatory for Human Rights, more than 37,000 people have died since the uprising against President Assad erupted in March 2011, first as a protest movement and then as an armed rebellion.