Syrian opposition figures meeting in the Qatari capital, Doha, say they have made progress towards forging a broad-based leadership group sought by the international community.
Prominent dissident Riad Seif, who had proposed a Western-backed initiative to unite the opposition and form a transitional government, said on Thursday that he was "optimistic" an agreement could be reached.
The opposition is moving towards creating "a political leadership that would satisfy the Syrians and be recognised by the international community," Seif said.
He later added that the main opposition bloc, the Syrian National Council (SNC), had deferred a decision until after a final round of internal elections on Friday.
The SNC is hesitant since it would reportedly be given only 22 of 60 seats in the new group, to make room for activists from inside Syria.
Al Jazeera's Omar Al Saleh, reporting from Doha, said it was obvious from Thursday's drawn-out negotiations that the Syrian opposition remain divided, with "huge differences between the members of the Syrian National Council and other opposition figures".
"The international community and the core group of the 'Friends of Syria' that includes the US, France, Britain, Qatar, Saudi Arabia, as well as Turkey, are pushing for a new initiative to be adopted by the delegates," he said.
"That initiative calls for a coherent representative structure that would also represent those fighting inside Syria. Western diplomats are telling Al Jazeera that this is not going to happen any time soon."
Washington wants the opposition to reshape into a "government-in-exile".
Opposition leaders say such a body could be sited outside Syria or in zones now under rebel control.
Qatar's Prime Minister Hamad Bin Jassim Al Thani urged Assad's opponents to "unify their ranks and positions and to prioritise the interests of their nation and people over their own personal interests".
The search for a united front came as video emerged purporting to show rebel fighters shooting dead an unarmed man.
The United Nations and human rights groups say both pro-government and anti-Assad fighters are guilty of war crimes - and the latest video would appear to give more evidence for that.
"It shows the ugliness of the war," said Middle East analyst Joseph Kechichian. "Obviously this is a civil war going on and there are breaches of international conduct and human conduct ... This is not the first time and not the last. Unfortunately, we are going to see these more often."
Reacting to the footage, SNC's Radwan Ziadeh said: "It's a very shocking video and alarming." "We condemn all the human rights violations committed by the rebels or FSA [Free Syrian Army]. [But] we are not sure that who did this execution are members of the FSA."
Assad vows to stay
| SNC's Radwan Ziadeh speaks to Al Jazeera about
war crimes allegations raised against rebels
Meanwhile, a defiant President Bashar al-Assad rejected calls he seek a safe exit from the country, vowing he would "live in Syria and die in Syria," as fighting raged in Damascus.
"I am not a puppet. I was not made by the West to go to the West or to any other country," Assad said in English in an interview with Russia's RT television.
"I am Syrian, I was made in Syria, I have to live in Syria and die in Syria," he said, according to transcripts posted on RT's website.
On Tuesday, British Prime Minister David Cameron floated the idea of granting Assad safe passage from the country, saying it "could be arranged," although he wanted the Syrian leader to face international justice.
Assad also warned against foreign intervention in the country's escalating conflict, saying such a move would have global consequences and shake regional stability.
"We are the last stronghold of secularism and stability in the region ... it will have a domino effect that will affect the world from the Atlantic to the Pacific," the transcript said.
In a separate video extract of the interview, Assad added: "The price of this invasion, if it happens, is going to be big, more than the whole world can afford."
Many in Syria's opposition, including rebels waging fierce battles with pro-regime forces, have urged world powers to intervene to stop the escalating bloodshed.