WASHINGTON – A month after the Obama administration pledged stepped-up support for Syria’s armed opposition, the government of President Bashar Assad’s position has improved, with U.S. assistance to the rebels apparently stalled and deadly rifts opening among the forces battling to topple the Assad regime.

Government forces appear close to forcing rebels from the key city of Homs after a 10-day offensive, while an al-Qaida-linked rebel group Thursday assassinated a top commander from the more moderate, Western-backed Supreme Military Council, signaling what one British newspaper dubbed a “civil war within a civil war.”

And that’s only some of the recent setbacks for the Syrian opposition’s two-track struggle toward improved fighting capabilities and greater political legitimacy.

In the United States, political and logistical snags are preventing the distribution of promised military aid, while in Turkey, the exiled civilian Syrian Opposition Coalition remains mired in organizational turmoil.

The coalition’s prime minister, Ghassan Hitto, a naturalized American citizen, resigned his post days after the group elected a new chairman, Ahmed Assi al Jarba. Hitto and Jarba represent different factions in the organization, one backed by Qatar, the other by Saudi Arabia, with Jarba’s election representing a Saudi victory.

Jarba’s ascendency is also a defeat for the Syrian Muslim Brotherhood, which has dominated the exile opposition for years.

The biggest reversals, however, came inside Syria, where areas once solidly under rebel control have begun to slip away. That has cut into the opposition’s ability to provide aid to hungry, besieged communities — a key part of a strategy to prove it could govern Syria should Assad fall.

“The desperation is spreading. It’s becoming an issue in all the areas in which we operate,” said an official with the Assistance Coordination Unit, the Turkey-based opposition office that’s a clearinghouse for foreign aid.

The official, speaking on condition of anonymity, said plans are under way for the United States to release $500,000 immediately to help with emergency food baskets, mainly destined for Homs.

The unit estimates that 1.6 million food baskets are needed each month throughout Syria; just 150,000 are currently being provided, the official said.

But the unit is having growing difficulties in delivering the food baskets. In one rebel-controlled area in the countryside outside Aleppo, the official said, hungry residents have created a “blockade” to prevent the aid from reaching regime-held districts, arguing that opposition supporters should be the priority when it comes to food.

At another site in Aleppo, the official said, hard-line Islamist fighters seized the food at a warehouse before it could be distributed.

“They seized it and arrested all the members of the local council,” the official said.

Meanwhile, increased military assistance that the Obama administration promised in mid-June after it determined that the Assad government had used chemical weapons has stalled because Congress is divided over whether and how to arm the rebels.

That program was to be handled by the CIA, but Congress’ intelligence committees have yet to approve the program. On Friday, members’ offices declined to discuss the program.