As the United States military’s intervention in Iraq intensifies, so does the debate between legislative and executive branch officials about President Barack Obama’s muscular use of war powers.

In the past ten weeks, Obama has authorized the first U.S. combat operations in Iraq since the war ended in 2011, and sent in roughly 1,000 U.S. troops.

The U.S. operation in Iraq is likely to extend beyond the 60-day limit under the War Powers Resolution that triggers congressional approval, meaning Obama may need a different authority to continue the fight. The president has used the sweeping 2001 Authorization of the Use of Military Force, or AUMF, to fight terrorist groups across the globe, but many argue it was primarily intended to authorize combat operations in Afghanistan, which officially end in December. The latest Iraq intervention represents what may be Congress’s last, best opportunity to rein in the dramatic expansion of the commander-in-chief’s authority to wage war that has occurred in the last 13 years.

The irony is that Obama just one year ago declared he would cut back the very authority his aides are now reconsidering. He pledged to chart a new path forward when he laid out his vision for a new comprehensive national security strategy to guide U.S. foreign policy.

“The AUMF is now nearly 12 years old,” Obama said at National Defense University in May 2013. “Unless we discipline our thinking, our definitions, our actions, we may be drawn into more wars we don’t need to fight, or continue to grant presidents unbound powers more suited for traditional armed conflicts between nation states. So I look forward to engaging Congress and the American people in efforts to refine, and ultimately repeal, the AUMF’s mandate.”

Today, gone is the talk of curbing unbound presidential powers to wage war. As the clock ticks, and Obama extends air attacks on Islamic State fighters, administration officials argue that the commander-in-chief is operating within his authority.

“We comply with the War Powers Act and informed Congress on how many people we have,” Defense Secretary Chuck Hagel said on Thursday. “This is not about mission creep.”

But Obama’s team quietly is considering whether they can use the original AUMF to shore up the president’s authority to conduct the growing U.S. military operation in Iraq.

“The president has the authority to take these actions,” National Security Council spokeswoman Caitlin Hayden told Defense One on Aug. 15. Obama has kept Congress appraised, she said. If the Iraq operation continues past Oct. 7, however, Hayden demurred, “It would be speculative to discuss how the 60-day provision in the War Powers Resolution would apply to these two specific and limited U.S. military operations.”

But, Hayden said, “We are reviewing the applicability of the 2001 AUMF to this situation, which would be in addition to the president’s constitutional authority as noted in the War Powers Resolution report.”

It’s a notable shift from the administration’s position that Obama would work with Congress to ultimately sunset the AUMF altogether. The administration continues to support the repeal of the 2002 AUMF that authorized the Iraq War of 2003-2011.

The president has few good options to face the unprecedented, urgent threat the Islamic State group poses. In potentially attempting to leverage the Bush’s administration’s legal framework, Obama could be committing U.S. forces to another open-ended intervention in Iraq, continuing the precedent set by his predecessor and locking in his successor.

Haunted By Votes To Start War and Promises to End It

As Islamic State fighters in the past six months steadily overran cities familiar from the Iraq War—Fallujah, Mosul—White House and congressional officials grew increasingly wary of the U.S. being pulled into another limitless war like the one many of them voted for more than a decade ago.

The 2001 AUMF that Congress passed in the fearful days following the Sept. 11 attacks has been called the most far-reaching, open-ended expansion of the executive’s powers in U.S. history. Though the AUMF’s mere 60 words made no mention of al-Qaeda or Afghanistan, they provided President George W. Bush the statutory authority for the war in Afghanistan and on “terror,” and the legal underpinnings for almost any use of U.S. military force to counter terrorism anywhere across the globe for the past 13 years.

John Bellinger, who served as legal advisor to the National Security Council and the State Department under Bush, was in the White House on 9/11 and later represented the administration before the 9/11 Commission and helped create the director of national intelligence. He described the AUMF as, “extremely expansive.”

“An enormous amount of counterterrorism actions—drones, detention, Guantanamo, the war in Afghanistan, the PSP [President’s Surveillance Program]—all hung on those 60 words,” Bellinger told Defense One Thursday.

Neither the 2001 nor the 2002 AUMF includes any expiration date, meaning both are still in effect, though both state they can’t supersede any requirement of the War Powers Resolution.

In the aftermath of Vietnam in 1973, Congress passed the War Powers Resolution over President Richard Nixon’s veto. The resolution stipulates that the president can only send troops into hostilities or imminent hostilities for 60 days without Congress declaring war or providing a specific authority to do so. That time can be extended for 30 days to allow for withdrawal, but only for a maximum of 90 days.

Like several presidents before him, Obama’s compliance with the War Powers Resolution has been inconsistent. In 2011, White House officials argued the U.S. military’s intervention in Libya did not amount to hostilities and thus didn’t require authorization from Congress under the War Powers Act. When considering air strikes against Syria last year, Obama said he could act without congressional approval because the situation represented a potential threat to the U.S., but he also sent Congress a War Powers Resolution report and said lawmakers should decide. They never did.

"Obama has been all over the map with respect to his uses of force, and when he has or hasn’t gotten congressional authorization," Bellinger said.

When Obama did eventually authorize air strikes in Iraq on Aug. 7, he acknowledged the roots of his reticence were tied to his opposition to the Iraq War. “I ran for this office in part to end our war in Iraq and welcome our troops home, and that’s what we’ve done,” he said. “As commander-in-chief, I will not allow the United States to be dragged into fighting another war in Iraq.”

‘United In Our Resolve’

Ten weeks after the Islamic State’s push into northern Iraq, Obama has now sent Congress four War Powers Resolution letters regarding Iraq—potentially the most concentrated period of presidential war powers reporting in U.S. history, according to Bellinger. On Wednesday, Pentagon officials acknowledged they were considering sending up to 300 additional U.S. troops to shore up security in Baghdad, which could push the U.S. presence beyond 1,000.

White House spokesman Josh Earnest said that senior members of Obama’s national security team reached congressional leadership and members of key committees in advance of Obama’s Aug. 7 announcement that he had authorized air strikes. Earnest noted that members of both parties backed the president’s decision.

But after initially expressing widespread support for the air strikes—of which a majority of Americans approve—as the U.S. involvement in Iraq has deepened, a growing group of lawmakers from both parties have called for Obama to come before Congress for authorization.

"We may not have declared it a war, but when we're dropping bombs and they're apparently beheading our citizens it certainly looks like war," said Rep. Adam Schiff, D-Calif., ranking member of the House Intelligence Committee, on Tuesday. But on Thursday, he cautioned, “We shouldn’t allow this horrible act to provoke us into doing things that are counterproductive…There’s nothing ISIS would like more than having us reintroduce ground troops into Iraq.” Schiff said lawmakers need to push for authorization for the use of military force in Iraq and can’t “abdicate our responsibility here.”

“We are finding out the authorizations in place are pretty tenuous,” Sen. Ron Johnson, R-Wis., said last week, referring to a meeting between Obama and members of the Senate Foreign Relations and Armed Services Committees to discuss the situation in Iraq. "He is going to need authority to deal with this new asymmetric threat.”

Sen. Tim Kaine, D-Va., told The New York Times that at the meeting, Obama responded to calls for congressional authorization. “Guys, you can’t have it both ways here,” Obama said, according to Kaine. “‘You can’t be ducking and dodging and hiding under the table when it comes time to vote, and then complain about the president not coming to you’ for authorization.”

Members of Congress feel last week’s airstrike campaign near Mosul “changes the debate,” one Senate aide described, calling the administration’s argument that protecting the dam protected U.S. citizens “a stretch.”

“You’re gonna look senators in the eye and say, ‘We took air strikes at Mosul Dam in order to protect personnel in Baghdad’?” the aide said. “If it’s about ISIS directly threatening U.S. personnel and facilities, the president’s Article 2 authorities stand. Once you’re undertaking kinetic action not explicitly tied to U.S. personnel and facilities, you need to understand the legal basis for doing those strikes.”

"Certainly executive branch lawyers believe the president also has constitutional authority to use force to protect U.S. national security more generally, which would go beyond just an immediate threat,” Bellinger said, “but the farther the president moves from using force to protect the country, to a threat against American interests, and more to protecting other people or other countries, the more pushback that he’s gonna get from Congress."

The administration’s very consideration of the AUMF’s application for the latest operation in Iraq indicates that it believes it is already stretching the limits of the president’s powers, which are certain to be tested further if the mission is expanded to the long-term strategy Pentagon officials have deemed necessary to defeating ISIL.

At a May Senate Foreign Relations Committee hearing on the Iraq and Afghanistan AUMFs, Stephen Preston, the top lawyer for the Defense Department, defended the continued use of the 2001 AUMF—but made no mention of ISIL or Iraq.

“The Executive Branch interprets the AUMF to authorize the use of force against al-Qa-ida [sic], the Taliban, and associated forces,” Preston said. The concept of an “associated force”—a term also excluded from the AUMF—“is based on the well-established concept of co-belligerency in the laws of war.” But he also said, citing guidance Obama laid out in his National Defense University speech, that in order for the U.S. to take “lethal counterterrorism action beyond the Afghan theater” a target has to threaten Americans.

Counterterrorism czar Matthew Olsen said last month that the space across Syria and Iraq is now the epicenter for recruiting, training and planning for direct attacks on Western targets. And on Thursday, Hagel and Chairman of the Joint Chiefs of Staff Gen. Martin Dempsey unequivocally stated that ISIL poses a threat to the U.S. “ISIL is as sophisticated and well-funded as any group that we have seen,” Hagel said. “They’re beyond just a terrorist group.”

But Bellinger believes that administration lawyers cannot “in good conscience” conclude that the Islamic State is an associated force with al Qaeda. “Fourteen years later the U.S. is now facing threats from people who, like ISIL or some of these groups, really are not associated with those who carried out the 9/11 attacks,” the one restriction of the AUMF, he said. “The president needs to have the authority to protect the country against those groups.”

An aide to House Armed Services Committee Chairman Buck McKeon, R-Calif., told Defense One that the National Security Council itself is deeply divided on continuing to apply the AUMF. “Even we agree it is being increasingly strained, and as you wind down operations in Afghanistan you have to look at how you are going to design the AUMF going forward. But we don’t necessarily agree with what some in the White House seem to want to do, which is to wind it down,” the aide said. “But there is a clear need to certainly refine it…if for no other reason than they are struggling to find a way to bring ISIS under the umbrella, under the AUMF, to justify broader actions.”

If inter-agency legal teams determine that the 2001 AUMF applies to the fight against the Islamic State, it would simply be a matter of sending a memorandum to Congress, the Senate aide said. Operations could then continue in Iraq with “blanket legal cover,” and without a vote. If the administration decides to formally expand the mission in Iraq into a broader campaign against the Islamic State, Obama would almost certainly need to seek new authorization. If the administration doesn’t get separate authorization, the 60-day limit should hit right at Congress’s most vulnerable, and busiest, time.

Once Congress returns from its long summer recess, it has only 12 days of work before departing for October’s run-up to the midterm elections. On Oct. 7, 60 days after Obama’s announcement of air strikes, both chambers won’t even be in session.

Congress currently has at least five measures to consider that could the curb war powers authority: two to repeal the 2002 AUMF, introduced independently by Sens. Rand Paul, R-Ky., and Senate Foreign Relations Committee Chairman Robert Menendez, D-N.J.; one to repeal the 2001 AUMF, from Rep. Barbara Lee, D-Calif., the only member of Congress to vote against it; and two passed by the House just before the long August recess, intended to block Obama from deploying or maintaining forces “in a sustained combat role” in Iraq without specific statutory authorization.

Several of these have been referred to Menendez’s Foreign Relations committee, which has jurisdiction to examine interventions abroad. The potential for classified briefings and a public hearing on Iraq upon Congress’s return in September is being discussed between Congress and the White House, the aide said, and though there isn’t much time to squeeze either in before the midterms, those would be the first steps toward making determinations about Obama’s legal authorities in Iraq.

Bellinger said, “Part of it, I think, is the politics of the situation right now—[Obama] would not want to put it to Congress, and particularly congressional Democrats, to ask them to vote for the use of force in Iraq in an election year. He already saw what happened with respect to Syria, and ISIL is probably a greater threat to us here, in Iraq.”

But the Senate aide said members of Congress, whether calling for oversight or dodging taking a stance, are sensitive to the potency of the threat as well. “There are many that would prefer not to take that vote and would be fine with them using the 2001 AUMF. But for certain members of Congress and certain members of this administration at this time, that’s a really difficult call to make.”

“It gets beyond the Middle East and North Africa. It’s about providing them flexibility. For national security, to repeal an AUMF without a new one, given that terrorism is still a serious issue, wouldn’t be a prudent course.”

In recent days, Obama officials’ tone has taken on a new heat, laying the rhetorical groundwork for an expanded mission in Iraq. “We’ve made very clear time and again that if you come after Americans, we’re going to come after you wherever you are. And that’s what’s going to guide our planning in the days to come,” deputy National Security Counsel advisor Ben Rhodes said Friday, noting the Islamic State’s roots in al Qaeda several times. “So we’re actively considering what’s going to be necessary to deal with that threat, and we’re not going to be restricted by borders.”

“Going forward, we would obviously have a legal justification for any action we take,” he continued. “And I do want to be clear—we would consult with Congress. This is, again, a problem that we have to deal with as a nation, and so whether it's our ongoing operations in Iraq or additional steps that may need to be taken against ISIL, we would carry those out in very close consultation.”