The Obama administration is open to limits on the duration of its military efforts in Iraq and Syria and on the potential use of ground forces in a new war authorization against the Islamic State, a top presidential adviser said Wednesday.

Tony Blinken, currently President Barack Obama’s deputy national security adviser, said discussions would continue with Congress on updating the legal basis for the U.S. intervention.

There has been no progress on an authorization in the two weeks since Obama vowed to coordinate with lawmakers on establishing a stronger legal basis for military action. That has prompted growing frustration among Republicans and Democrats with the White House.

Blinken, nominated by Obama to be Secretary of State John Kerry’s deputy as the No. 2-ranked U.S. diplomat, was testifying Wednesday at a confirmation hearing before the Senate Foreign Relations Committee. He was asked by the chairman, Democratic Sen. Bob Menendez of New Jersey, if a three-year limit on operations and a prohibition on a large-scale ground combat mission were reasonable.

Blinken said those conditions would be “appropriate” and could form a “good basis” for the law.

He then told Sen. Bob Corker, R-Tenn., the administration sees a “targeted, focused” law specifically designed for fighting the Islamic State as an important part of building “broad support” on an issue of war and peace. Corker will become the panel’s chairman when Republicans take over the Senate majority in January.

The toughest bout of questioning came from Sen. John McCain, R-Ariz., who asked Blinken if he was wrong two years ago when he said “what is beyond debate … is that Iraq today is less violent, more democratic and more prosperous, and the United States more deeply engaged there than at any time in recent history.”

Blinken said he stood behind his assessment of that time period.

After his party’s drubbing in midterm elections, Obama said he’d work with Congress during the current lame-duck session on a new authorization for the U.S. intervention in Iraq and Syria. It reflected that even many supportive lawmakers reject the administration’s legal justification based on a 2001 authorization to fight al-Qaida and another a year later to invade Iraq.

The Islamic State group didn’t exist at the time of either vote, emerging only recently from the al-Qaida movement. They’ve primarily fought each other since.

Nevertheless, Republicans and Democrats say the administration isn’t prioritizing a new authorization, having yet to outline what it wants from Congress or dispatch top officials to testify. As a result, congressional aides say, the law won’t come this year and it’s unclear when the matter may be taken up in 2015.

A delay won’t immediately affect the American war effort in Iraq and Syria. Obama insists he already has the authority to conduct the counterterrorism mission and U.S. officials haven’t indicated they’d halt military activity if lawmakers vote down any authorization bill.

But U.S. officials and members of Congress worry the tenuous legal rationale for fighting could become divisive over time on a national security issue all say should be apolitical. And for members of Congress who’ve emphasized their constitutional responsibility to declare war, their lack of action more than three months into the U.S. bombing campaign is something of an embarrassment.

Fresh off their election triumphs, Republican leaders are waiting on Obama.

House Speaker John Boehner, R-Ohio, and soon-to-be Senate Majority Leader Mitch McConnell, R-Ky., want the president to send over a draft authorization and to start working to build bipartisan support. That sentiment is shared by Corker, whose committee would likely be the starting point for the process next year.

Menendez hoped to advance the cause of a new authorization this week. But he canceled a hearing scheduled Tuesday when he couldn’t get Kerry, Defense Secretary Chuck Hagel or another official of similar stature to present the administration’s arguments.

More pressing issues may be at stake for Congress and the administration.

Permission to arm and train Syrian rebels, a central plank of Obama’s strategy to defeat the Islamic State militants, expires next month. Congressional leaders are trying to reauthorize the program as part of a larger spending measure to keep the government running. Obama also is seeking $5.6 billion to cover the military costs in Iraq and Syria. Those funds may come in an annual defense bill senators are trying to complete by year’s end.

(AP)