Sen. Bill Nelson, D-Fla., plans to introduce legislation next week that would give President Barack Obama definitive authority to launch airstrikes against the Islamic State terror group in Syria — as senators on both sides of the aisle ramp up calls for military action.  

“This will ensure there’s no question that the president has the legal authority he needs to use airstrikes in Syria,” Nelson said in a release.  

While Obama has ordered airstrikes against ISIS in Iraq, some policy experts have questioned whether the administration has the clear legal authority — independent of Congress — to broaden the air campaign to strike targets in Syria. Nelson’s legislation is designed to allay those doubts. His comments come after reports that ISIS released a video appearing to show the murder of Steven Sotloff, an American journalist from Florida who disappeared in Syria.  

The purported Sotloff video followed the release of a similar one released two weeks ago of the execution of American journalist James Foley.  

“Let there be no doubt, we must go after ISIS right away because the U.S. is the only one that can put together a coalition to stop this group that’s intent on barbaric cruelty,” Nelson said.  

Obama’s National Security Council called the video appalling, if true. The extremist group is also known as the Islamic State of Iraq and the Levant, or ISIL.  

“We have seen a video that purports to be the murder of U.S. citizen Steven Sotloff by the Islamic State of Iraq and the Levant (ISIL),” the NSC said in a release. “The intelligence community is working as quickly as possible to determine its authenticity.  If genuine, we are appalled by the brutal murder of an innocent American journalist and we express our deepest condolences to his family and friends.  We will provide more information when it is available.”  

Sen. Marco Rubio, R-Fla., also called for a stern response.  

“The horrifying clarity of ISIL’s message toward America should have been met from the beginning with an equally clear opposing message,” Rubio said.  

“If we do not act now to assist our Iraqi partners and moderate Syrians who oppose ISIL, as well as utilize our own forces to directly target ISIL’s leadership, the result will be more suffering and tragedy for our people,” Rubio added.  

Sen. Lindsey Graham, R-S.C. and Sen. Jeanne Shaheen, D-N.H., similarly urged appropriate action.  

“It is time we act decisively against ISIL wherever it resides,” Graham said.  

“Mr. President, if you can’t come up with a strategy, at least tell us what the goal is regarding ISIL,” Graham said in response to last week’s press conference speech where Obama said he didn’t have a strategy yet  to take on the Islamic State in Syria.  

Shaheen echoed the others. “ISIL must be stopped, and we must use every tool at our disposal, short of introducing ground forces in combat roles, to put an end to the threat they pose to our national security,” Shaheen said.