President Barack Obama went to Congress several years ago to pass an Authorization for Use of Military Force (AUMF) for US military campaign against ISIS, but the effort failed to gain traction amid weariness from lawmakers to vote on the war and disagreements over the details of the authorization.
Ultimately, Congress never took a full vote on an ISIS war authorization.
The Obama administration began striking ISIS in Syria
in September 2014, which prompted congressional critics of the military action to call for Congress to vote on the war. Initially, the White House did not send Congress a war authorization, saying it was legally justified to strike ISIS based on the war authorization approved after the September 11, 2001, attacks.
But Congress began its own effort, and a war authorization was approved
in the Senate Foreign Relations Committee in December 2014, when Democrats still controlled the upper chamber.
That effort didn't go any further as the Senate switched from Democratic control to Republican control following the 2014 midterms.
In February 2015, Obama sent Congress a draft AUMF
, which he said in a speech
that congressional passage of the measure makes the US "strongest" in the fight against ISIS.
There were disagreements over the measure almost immediately, however, underscoring the difficulties in getting Congress to agree on what a war authorization should look like.
Obama's draft authorization included limitations on "enduring offensive ground combat operations," as well as a three-year window before it would have to be re-authorized.
The restrictions were a recognition that Democrats would insist on a clear scope for any war authorization, as well as concerns stemming from the Iraq War over the deployment of US ground troops in the Middle East.
But Republicans balked at those conditions, saying that they were opposed to limiting the military options of the commander-in-chief, for Obama or any future US President.
The disagreement, as well as Republicans' skepticism of Obama, stalled the measure. By April 2015, then-House Speaker John Boehner was already saying
Obama would not get an AUMF.
"Until the President gets serious about fighting the fight, until he has a strategy that makes sense, there's no reason for us to give him less authority than what he has today. Which is what he's asking for," Boehner said.
The 2002 Iraq War vote -- the last time Congress passed a war authorization -- also loomed over lawmakers, who remembered how then-Sen. Hillary Clinton's vote for the war was used against her years later on the presidential campaign trail when the war went sour with the public.
Both Trump and Clinton said during the campaign that they agreed with the Obama administration assessment that the war was legally justified by the 2001 AUMF, which was intended to fight al Qaeda and passed a decade before ISIS existed. But they also said they'd support congressional approval of the ISIS war.
Now many of the same lawmakers who failed to get Congress to pass a war authorization for Obama are hoping they'll have better luck with Trump in power -- and Thursday's airstrike against Syrian government
targets has sparked a new round of calls for an AUMF.
"We had a bill in for a couple of years nobody was interested in -- we tried to wordsmith differences between Democrats and Republicans -- so we're actually exploring some different ways of coming at it," Sen. Tim Kaine, a Virginia Democrat who's been one of the biggest advocates for a war vote, told CNN l