The Supreme Military Command and its forces, known collectively as the Free Syrian Army, are reeling as 40 or more affiliates this month have signed onto two new umbrella groups, both with agendas that are at odds with the U.S.-backed opposition’s long-stated vision of a democratic, pluralistic Syria.

If the project to build rival Islamist commands succeeds, opposition activists and Middle East analysts warn, the Supreme Military Command is likely to fizzle quickly, essentially ending talk of a “moderate” rebel force to counter the influence of Islamist insurgents, including at least two factions aligned with al Qaida.

“Because we’re short on ammunition, short on supplies, some of our groups are going to them. The Islamists have their own supplies,” said Louay Meqdad, a spokesman for the Free Syrian Army. “We’re asking the international community: Please don’t leave our people to choose between joining the extremists and surrendering to Bashar Assad.”