The proposal is being prepared for possible use if President Donald Trump resumes strikes, with Republicans expecting fresh notification if hostilities restart.
Under the War Powers Act, introducing it during the first 30 days of the next 60-day hostilities period could trigger expedited Senate consideration and a quick floor vote.
Aides are also examining whether the measure would eventually need 60 votes or only a simple majority, while the draft would likely bar ground troops and set a time limit.
With the War Powers clock expired, who now decides if America goes back to war with Iran?
How can a limited military authorization prevent an uncontrollable war in the volatile Middle East?
Can the global economy survive another blockade of the world's most critical oil chokepoint?