Hijab’s position highlights the deep differences over Assad’s fate and a future political transition in Syria between parties to the talks.

Syria’s opposition wants a political transition without President Bashar al-Assad, said Riad Hijab, who was chosen by Syrian opposition groups as coordinator of a negotiating body to lead future peace talks.

The United States, Russia along with Iran, Saudi Arabia and major European and Arab powers outlined a plan last month for a political process in Syria leading to elections within 18 months. It includes a nationwide ceasefire and six months of talks beginning in January between Assad’s government and the opposition on forming a unity government.

U.S. Secretary of State John Kerry, Russian Foreign Minister Sergei Lavrov and more than a dozen other ministers will meet for a third time in New York on Friday, to keep up the momentum to get a deal to end the nearly-five-year-old war.

Hijab, elected on Thursday by an opposition body set up in Saudi Arabia last week, said Security Council resolutions and the Geneva 1 2012 roadmap provided for a transition without the president and a transitional governing council with full executive powers.

“We are going into negotiations on this principle, we are not entering talks (based on) anything else. There will be no concession,” he told reporters on Friday.

Hijab’s position highlights the deep differences over Assad’s fate and a future political transition in Syria between parties to the talks.

Western diplomats have said Western powers, Turkey, Saudi Arabia and others have reluctantly agreed to allow Assad to remain in place during a transition period, a compromise that has opened the door to a shift on Russia’s stance.

Russia has meanwhile made clear to Western nations that it has no objection to Assad stepping down as part of a peace process, in a softening ahead of the New York talks of its staunch and open backing of Assad, diplomats said.

Iran has also been a firm ally of Assad and is intervening militarily on his behalf against anti-government forces in the five-year civil war.

On Thursday, Hijab, who defected from Assad’s government in 2012, got the backing of more than two thirds of the 34 delegates from movements called to Riyadh by world powers in a bid to unite them and settle years of wrangling and rivalries.

The members of the body are representatives of political opposition groups inside and outside Syria.

It also includes representatives of fighting groups such as the powerful Islamist Ahrar al-Sham and a number of Free Syrian Army units that have received military support from states opposed to Assad such as Saudi Arabia and the United States.

But it does not include the al Qaeda-linked Nusra Front, or Islamic State of Iraq and Syria (ISIS), which are among the main players opposing Assad.

Divisions within the Syrian opposition have hampered efforts to resolve the conflict.

“We will not accept any pressure. The aims of the revolution and the international resolutions, we cling to them, and we will not give them up,” Hijab said.

“I call it a battle in terms of the negotiation process and the political process. It is in tandem with what is happening on the ground …

“Our first option is the peaceful option. But if it’s not complete, the other option will continue and will not stop … until it fulfils the aims of toppling the illegitimate regime.”

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