WASHINGTON - US lawmakers say they are on the verge of taking a "war vote" as they consider whether to back President Barack Obama's campaign to destroy Islamic State, and despite broad support for action many fear being drawn into a quagmire.
The White House wants Congress to approve $500 million to train and arm moderate Syrian rebels to battle Islamic State militants, a show of confidence for administration officials as they try to form an international coalition.
The beheadings of two US captives by Islamic State have steeled lawmakers to the need for more military action, and both Democratic and Republican congressional leaders were supportive of Obama's plan on Wednesday.
But some Republicans in particular say they want more information from the administration about its wider strategy to combat global terrorism, and many would prefer a broad vote rather than one focused on funding.
"This could be taken by some as a war vote," said House Appropriations Committee Chairman Hal Rogers, adding that he has reservations about providing weapons that could fall into enemy hands.
"There are so many unknowns that we are dealing with here, it's too early to make any decisions," the Kentucky Republican told reporters shortly before Obama told Americans in a speech on Wednesday night that he had authorised an escalation of his campaign against Islamic State.
Republican Senator Rand Paul, also from Kentucky and normally a leader of his party's isolationist wing, said he would support military action against Islamic State, but wants Obama to "follow the Constitution" and seek congressional authorisation.
Just a year ago, US lawmakers recoiled at the thought of military strikes against Syria's government for using chemical weapons. They handed Obama an embarrassing foreign policy defeat as anti-war Democrats joined isolationist Republicans in a rare show of bi-partisanship that killed his request for strikes.
Democrats are crossing the aisle again, this time as they voice strong support for attacking Islamic State, though the overwhelming majority of lawmakers from both parties oppose the idea of sending in any US ground troops.
"I often disagree with the president's foreign policy, but you've got to come together as a nation to stand up to ISIS," said Representative Luke Messer, an Indiana Republican, using another name for Islamic State.
While criticising Obama's previous handling of the threat from Syria, Representative Tom Cole, an Oklahoma Republican, predicted Obama would ultimately get bipartisan support.
"You back presidents up in a situation like this," Cole said.
Obama has requested that funds for training rebels be included in a stop-gap funding bill that would avert a US government shutdown on Oct. 1, the start of a new fiscal year.
The White House has said Obama he does not believe he needs Congress' formal authorisation to attack Islamic State.