IRBID, Jordan — The main Western-backed Arab rebel group in Syria appears on the verge of collapse because of low morale, desertions, and distrust of its leaders by the rank and file, threatening U.S. efforts to put together a ground force capable of defeating the Islamic State and negotiating an end to the Syrian civil war.

“After five years of this war the people are just tired … and so are our fighters,” said Jaseen Salabeh, a volunteer in the Free Syrian Army, which was formed in September 2011 by defectors from the army of Syrian President Bashar Assad.

The Free Syrian Army, or FSA, some of whose members are trained by the Central Intelligence Agency, is the biggest and most secular of the scores of rebel groups fighting the Assad government. Although defeating the Islamic State is the focus of Western attention, the U.S. believes there can be no lasting peace in Syria, and no elimination of the Islamic State there, as long as Assad remains in power.

In order to deal with both the Islamic State and the future of Assad, Secretary of State John Kerry and Russian Foreign Minister Sergey Lavrov have brokered a plan to bring the Syrian government, which Russia supports, and all “moderate” rebel groups to the negotiating table in Vienna next month. The aim is to build a coalition to wage a counterterrorism campaign against the Islamic State militants and prepare for democratic elections within the next 18 months.

With an estimated 35,000 fighters, the FSA remains the biggest rebel group and is a key element in the U.S. strategy. Islamic State fighters are believed to number about 30,000 but spread over a wider area of both Syria and Iraq.

If the FSA can’t be relied on as a strong partner, however, the U.S. and its Western partners would have to turn to an assortment of smaller hardline Islamic militias — backed by Saudi Arabia and Qatar — that the West fears are too militant to reconcile with the secular government. Kurdish rebels, known as the YPG, have fought well in Kurdish areas but are not considered a viable option in Arab parts of the country.

Unlike the Islamic State and other more extremist groups, however, the FSA has failed to achieve any significant victories or create a “liberated” zone of its own. On many occasions, its former fighters say, FSA units have cooperated closely with the al-Qaida-linked Nusra Front, which is strong in the north and shares the same battlespace as the FSA in southern Syria.

“The lack of battlefield success has mitigated against them,” Ed Blanche, a Beirut-based member of London’s International Institute for Strategic Studies and an expert on Middle Eastern wars, said of the FSA. “They haven’t been getting significant (outside) support because they haven’t been showing results.”

Among other problems, Salabeh and others say, FSA fighters are losing faith in their own leaders.

“They regularly steal our salaries,” said Salabeh, who came to this city in northern Jordan after being wounded in battle and now intends to stay here. “We’re supposed to get $400 a month, but we only actually receive $100.”

He also complained of lack of support for those killed or wounded in battle. Fighters who lost legs in the fighting were reduced to begging inside the massive refugee camps in northern Jordan.

“If somebody is wounded, they just dump him in Jordan and abandon him,” he said. “Widows of martyred fighters also receive nothing after their deaths.”

As a result, many FSA men in southern Syria were abandoning the group, usually leaving for Jordan or joining the estimated 15,000-strong Nusra Front, according to Saleh and other Syrians interviewed in northern Jordan. By contrast, the Nusra Front reportedly pays its fighters $1,000 a month and cares for its wounded members, paying their medical bills and providing for the families of those killed in combat.

The situation has gotten so bad, Salabeh said, that some FSA fighters are questioning the reason for continuing the conflict. He said a growing number believe the time has come for a ceasefire even it means cooperating with Assad.

“After all, Bashar isn’t all that bad,” Salabeh said.

Karim Jamal Sobeihi, a refugee from southern Syria and a self-described FSA supporter, said the opposition’s main problem was that various groups owed their allegiance to foreign governments that provide the money and, therefore, the rebels cannot agree on unified positions. This included the FSA, which itself consists of many different factions, he said. That made the radicals — with their Islamist ideology and independent streak — more attractive to those willing to fight the regime, he said.

“There is total disunity. Syria has become a battleground for America, Russia, Turkey, Saudi Arabia and other countries and terrorists of all kinds,” Sobeihi said.

Analysts in Jordan and Lebanon, which both host huge numbers of Syrian refugees, have blamed the FSA for allowing the revolution that broke out in early 2011, to be taken over by hardline jihadist groups.

Hisham Jaber, a retired Lebanese general and military analyst, said the international focus on fighting the Islamic State rather than ousting Assad indicates the West and its Arab allies recognize that Assad cannot be overthrown by military means — especially after Russia’s intervention on the Syrian president’s behalf.

This has in turn demoralized FSA troops, Jaber told Stars and Stripes during an interview in Beirut. He said FSA units in both the north and south were cooperating more closely with the better-organized and better-funded Nusra Front, regardless of its al-Qaida connections.

“In contrast, Nusra is winning the hearts and minds of the people, and positioning themselves as moderates despite their al-Qaida links,” said Elias Hanna, a former Lebanese general and professor of geopolitics at the American University of Beirut.

lekic.slobodan@stripes.com