John R. Allen, the Special Presidential Envoy for the Global Coalition to Counter ISIL, will leave the job in November, according to Bloomberg, which cited four anonymous Obama administration officials when reporting on the yet-public information.

Allen is reportedly frustrated with a lack of resources to counter the jihadist group, according to US officials. Allen had unsuccessfully lobbied administration officials for increased tactical air control teams to more efficiently target IS on the ground in Iraq, Bloomberg reported. Meanwhile, administration officials have portrayed his decision as one made out of concern for his wife’s poor health.

After originally committing to six months, Allen stayed in the position for an additional six months at the request of US Secretary of State John Kerry. In the near term, his deputy, Ambassador Brett McGurk, is expected to assume his duties.

Allen has defended the Obama administration’s IS strategy, including on one occasion earlier this month when he told ABC News that airstrikes have been successful in some areas of Iraq and Syria, where IS controls large swaths of territory.

“Where we were a year ago today, I wasn’t sure how it was going to unfold,” said Allen, who took the envoy post in September 2014. “It was not clear to me even that Iraq would survive this. In the intervening months, we’ve seen remarkable progress in many respects.”

Allen’s departure comes amid comments made last month by the incoming Marine Corps Commandant, Lieutenant General Robert Neller, that the US-led coalition’s war on IS has hit a “stalemate.” Also in August, the New York Times reported that characterizations of the campaign against IS may have been skewed, as intelligence assessments have been presented in an increasingly optimistic light, while real success in defeating IS jihadists is still out of sight a year after constantly bombing IS targets.

While Allen, a retired four-star general and former commander of the International Security Assistance Force in Afghanistan, did secure permission for the US to use Turkey’s Incirlik Air Base for Syrian bombing operations, other initiatives have not panned out. Despite US efforts, IS has maintained control of Mosul, Iraq’s second-largest city, and expanded its reach into Ramadi, the largest city in Western Iraq’s Al-Anbar Governorate.

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In July, Allen said “ISIS is losing” the fight against the US-led coalition, even as other administration officials said Islamic State was the largest threat to the US homeland.

“As they get weaker at the core…it also makes it more difficult to influence individuals and smaller groups, so both things can happen simultaneously,” Allen told The Daily Beast at the time.

“We can see the individual threat potentially going up domestically, while we are squeezing ISIL at the strategic level in the region in Iraq and Syria, so those comments are not inconsistent.”

On September 10, 2014, Obama announced a “comprehensive and sustained counterterrorism strategy” to “degrade, and ultimately destroy” Islamic State. US drones and warplanes had already been targeting the group since early August of 2014, after IS killed two American journalists it had been holding hostage.

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Obama outlined a four prong strategy against Islamic State in the announcement: Whileconducting a “systematic campaign of airstrikes,” the US would “increase our support to forces fighting these terrorists on the ground,” use counter-terrorism capabilities to prevent IS attacks elsewhere, and “provide humanitarian assistance to innocent civilians” displaced by the group.

Initially nameless, the campaign was dubbed “Operation Inherent Resolve” in October 2014. Since then, the US and its allies have flown more than 53,278 sorties “in support of operations” in Iraq and Syria, conducting more than 6,700 airstrikes at an expense of nearly $4 billion as of September 8, according to official information provided by the Pentagon.