DUBAI: Syrian opposition groups gather in Saudi Arabia Tuesday to unify their stance ahead of potential talks with the regime of President Bashar Assad, whose fate remains a point of contention.

It will be the first time representatives of the political opposition and military factions fighting the regime have come together since the conflict began in 2011.

Saudi Arabia is hoping to unite the opposition ahead of talks between parties to the conflict which world powers hope to hold before Jan. 1.

Some hundred representatives are likely to attend the meeting Wednesday, including Saudi-backed Jaish al-Islam (The Army of Islam), an amalgam of factions that include hardline Islamists, which is not listed as a terrorist group.

The Western-backed Southern Front coalition, operating in southern Syria, is thought to be another invitee, but has not said so officially.

There have also been reports that Ahrar al-Sham, perhaps the most powerful non-jihadi opposition force in the country, will be invited.

The group has not commented officially on the reports and declined request for comment on the issue.

The invitees do not include those considered to be “terrorist,” such as Daesh (ISIS) and Al-Qaeda’s Syrian affiliate Al-Nusra Front.

Kurdish factions are not invited.

“The mission is difficult and risky,” said Samir Nashar, a member of the Istanbul-based National Coalition, the main Syrian opposition grouping.

He said the aim was to “agree on a common and clear position concerning the future of Syria, the transition and the stance on [the fate of] Bashar Assad.”

Last month, top diplomats from 17 countries – including key international backers and opponents of Assad – met in Vienna in search of a political solution to Syria’s war, which has seen 250,000 people killed since March 2011.

Those nations included the United States and Saudi Arabia which back the opposition, and Russia and Iran, Assad’s main supporters.

They agreed on a fixed calendar for Syria that would see a transition government set up in six months and elections within 18 months.

Speaking of “core differences” over Assad’s fate, Nashar said he feared that “some groups close to states supporting the regime, could demand that Assad stays during the transition period.”

“This risks causing the failure of the meeting,” he said.

Groups supported by the United States, Saudi Arabia and Qatar demand Assad’s rapid departure, a condition that Iran and Russia continue to oppose.

“The opposition still demands the departure of Assad at the beginning of the transition period,” insisted Ahmed Ramadan, another National Coalition member.

“We cannot negotiate before agreeing in principle and having a date for the departure of Assad,” he then said.

Nashar added that although a cease-fire is a must, that “could not mean that we accept that Bashar Assad could stay during the transition [only] because he will stop killing.”

Meanwhile, the Syria-based opposition which is tolerated by the regime argues that Assad’s fate should be decided by the Syrian people.

“There is an international agreement that this issue should be decided by the Syrians,” said Hassan Abdel-Azim, who heads the National Coordination Committee for Democratic Change.

The recent deadly attacks by Daesh, mainly those in Paris last month, appear to have softened the positions of Western countries on Assad, especially France.

“A united Syria implies a political transition. That does not mean that Bashar Assad must leave even before the transition, but there must be assurances for the future,” French Foreign Minister Laurent Fabius said in an interview published Saturday.

His American counterpart John Kerry also urged Saudi Arabia and the United Arab Emirates to convince Syrian rebel groups to negotiate a cease-fire with Damascus, in an effort to isolate militants.

A U.S.-led coalition, including several Gulf and other Arab countries, in September 2014 launched an air campaign against Daesh.

Moscow mounted its own campaign in September this year, but the National Coalition accuses Russia of bombing Syrian rebels battling Assad’s regime.

Haytham Manna, co-founder of the opposition coalition Cairo Conference, said 20 members of his group would join next week’s talks.

Saudi Arabia, meanwhile, hopes to come out of the meeting with a “unified Syrian opposition, and to stop the Russians and others from claiming there is no Syrian opposition that is unified,” according to Saudi columnist Jamal Khashoggi.

This will ease the process of getting rid of Assad, he said.

Regional rival Iran, however, has warned that the Saudi conference would breach declarations made by both sides in Vienna seeking a list of mutually approved opposition groups.