Shocker.

WASHINGTON (Reuters) – Influential Republican Senator John McCain said on Tuesday he is working to modify a congressional resolution authorizing U.S. military force in Syria to include a “strict” timeline for Syria to turn over chemical weapons.

The amendment is a response to new diplomatic developments designed to ward off a U.S. military strike, highlighted by Russia’s agreement Monday to get Syria to turn over its chemical weapons.

Speaking on CBS’ “This Morning” program, McCain said he was “extremely skeptical” about such a diplomatic solution but that “to not pursue this option would be a mistake.”

“Some of us are already working on a modification to a Congressional resolution that would require strict timelines and strict guidelines that would have to be met as part of the authorization for the president” to use military force, he said.

McCain offered few specifics about his measure, but other lawmakers have also been floating proposals that would allow a certain window of time before allowing President Barack Obama to take further action, which could include air strikes.

Democratic Senators Joe Manchin and Heidi Heitkamp are pushing an alternative that gives the Assad government 45 days to sign an international chemical weapons ban and begin the process of turning over its weapons.