He was replaced by Abdul-Illah al-Bashir, a little-known rebel leader from the province of Quneitra who is fighting on the southern front and did not attend the meeting, the commanders said.
The move comes as the breakdown of peace talks in Geneva shifts attention back to the increasingly complicated battlefield in Syria, where the government of President Bashar al-Assad has steadily been making advances against the deeply divided rebels.
Even before the talks were suspended Saturday, Syrian opposition leader Ahmad al-Jarba, who has close ties to Saudi Arabia, had been signaling his intent to refocus on the military struggle against Assad by visiting the front line and promising rebel leaders that new weapons are on the way.
“You will get weapons, including quality weapons,” he said during a videotaped visit on Friday to Jamal Maarouf, an increasingly powerful rebel commander in the northern province of Idlib.
Several rebel commanders at Sunday’s meeting said Idriss had been replaced at the insistence of Jarba, who wanted to see a more effective leader in place ahead of the arms supply, which the Wall Street Journal reported on Saturday will include antiaircraft weapons.
The mild-mannered Idriss, who derived his authority primarily from the support he received from Western countries, was widely considered to have failed to provide meaningful leadership to the chaotic rebel movement or to have effectively channeled what little support he received to the rebels under his command.
His credibility collapsed further in December after Islamist rebels seized the warehouses he oversaw on the Syrian border, prompting a suspension of aid by his chief ally, the United States.
Idriss’s failure last month to respond to the needs of rebel units caught up in the eruption of fighting against the Islamic State of Iraq and Syria, an al-Qaeda splinter group, sealed his demise, said one of the commanders who voted him out. “When we started the fighting against ISIS, Idriss turned off his phones and couldn’t be reached,” said Ziad Haj Obaid, a commander from the eastern province of Deir al-Zour. “That was the main reason we replaced him.”
U.S. officials say they plan to quickly resume the provision of nonlethal aid, which mostly includes food and medicine. But it is expected that future deliveries will be made directly to rebel units rather than through the military command, said a U.S. official who spoke on the condition of anonymity because of the sensitive subject.