From Antiwar.com 
From the indispensable Just Foreign Policy :
Help Rand Paul Call the Question on War with Iran
Sen. Rand Paul introducing his amendment to S. 2101.
Before we have any military conflict with Iran, the Senate and the House should have at least one debate and vote on it. That’s what the Constitution and the law require; that’s what the public interest requires. And it would be better to start that debate now, when there is still a chance of rational discussion, than in the wake of some Gulf of Tonkin incident, when cable news and talk radio could steamroll Congress.
Kentucky Senator Rand Paul has called the question , blocking unanimous approval of a new Iran sanctions bill to force consideration of an amendment affirming that nothing in the bill would authorize the use of military force , and that military force would require explicit Congressional authorization.
Urge your Senators and Representative to support amending any pending Iran sanctions legislation to affirm that it does not authorize the use of military force and that any use of military force must be explicitly authorized by Congress.
[Please see the link at Just Foreign Policy to find your representative .]