President Barack Obama is poised in the next few days to ask Congress for new authority to use US military force against Islamic State (IS) militants.
But the senior Republican in Congress warned it will not be easy to pass the measure and that it will be up to Mr Obama to rally support from politicians and the public.
“His actions are going to be an important part of trying for us to get the votes to actually pass an authorisation,” Republican House Speaker John Boehner.
White House spokesman Josh Earnest responded that the administration is dedicated to getting a new authorisation with support from Republicans and Democrats.
That is even though the president has argued new authorisation is not legally necessary and has been ordering airstrikes on militant strongholds in Iraq and Syria for months.
“The president believes it sends a very powerful signal to the American people, to our allies, and even to our enemies, that the United States of America is united behind this strategy to degrade and ultimately destroy ISIL,” Mr Earnest said, using an acronym for IS.
“That across branches of government and even across political parties, even in this divided time in our nation’s political history, at least, that Democrats and Republicans are committed to this very important task.”
Mr Earnest declined to discuss specific provisions being discussed, such as how long the authorisation will last, what geographical areas it will cover and whether it will allow for the possibility of ground troops.
He said details are still being worked out with politicians from both parties, with the hopes of coming up with the authorisations can draw bipartisan support.
But senior House Democrat Nancy Pelosi said talks with the administration are focusing on a time frame of three years, while the other issues are still being worked out.
She told journalists it will be a challenge for wary Democrats, the White House, and Republicans seeking a broader use of military force to forge an agreement, but that she ultimately expects one to be reached.
Mr Obama has been relying on congressional authorisations that President George W Bush used to justify military action after the terrorist attacks of September 11, 2001.
Critics say the White House’s use of post-September 11 congressional authorisations is a legal stretch, at best.
The developments come after Islamic militants released a grisly video of the murder of a Jordanian Air Force pilot by burning him alive.
Ms Pelosi also said the US should “move quickly” to steer military aid to Jordan, which has begun a stepped-up campaign against the militants, including a series of air strikes in Syria.