Democrats on a Senate panel on Thursday unanimously supported a new authorization for military force against Islamic State jihadists without US ground troops, signaling their willingness to tie President Barack Obama's hands on war policy.
In a party-line vote, the Senate Foreign Relations Committee approved a three-year authorization for use of military force that would supercede the open-ended AUMF's passed in 2001 and 2002 in the aftermath of Al-Qaeda's 9/11 attacks on the United States.
The US-led coalition has already carried out some 1,100 airstrikes in Syria and Iraq since September targeting IS extremists in a bid to defeat the group, which has seized large swathes of territory, executed opponents and imposed harsh Islamic law.
Under the US Constitution, Congress has ultimate power whether to declare war.
There is broad consensus that lawmakers should fully debate the use of military force in Iraq and Syria, but that will occur in 2015 under a Republican-controlled Congress.
Democrats went on record however stressing the need to retain the power on declaring war, and underscoring their opposition to the White House's open-ended use of 12-year-old authorizations to conduct military action today.
The new AUMF would "envision boots on the ground, they're just not American boots," argued Democratic committee chairman Senator Robert Menendez.
He also warned that Congress taking no action would allow the White House to keep acting under earlier war-on-terror authorization.
"If we wait for an administration -- this or any other one -- to send us their language for an AUMF and they never do it... they have a veto over the constitutional imperatives and prerogatives to declare war," he said.
Obama has sent 3,100 US military advisers into the field to help coordinate the battle against IS, and said he was relying on the previous authorization against the Taliban and other "terrorists" of 2001, and the Iraq invasion authorization of 2002, to do so.
Many US lawmakers contest the legality of such actions.
"This is really in many ways a standoff between the parties... but also with the administration," Senate Democrat Barbara Boxer acknowledged.
"I draw another line in the sand as far as another ground war."
The administration is opposed to geographical limitations on military action or restrictions on ground troops.
US Secretary of State John Kerry has argued that the president must be free to adapt to future developments in the war against jihadists.
Republicans are largely in line with the White House, preferring to leave the president with sufficient flexibility to prosecute the war.
And Senator Bob Corker, the panel's likely incoming chairman, suggested it was unwise to pass a new force authorization amid confusion Obama's efforts to craft a successful plan for defeating IS.
"I have no earthly idea how the administration plans to go about degrading and destroying ISIS in Syria," an exasperated Corker told the panel.