Lorie Byrd has an idea what it should be, and Republicans would be wise to listen:

A few months ago, I wrote that the president should be making the argument Dick Cheney made in a brilliant speech in July 2003 to the AEI. He said that knowing what we knew then, prior to invading Iraq, and looking at it in the shadow of the 9/11 attacks, it would have been irresponsible NOT to take action to remove Saddam Hussein:

"Now the regime of Saddam Hussein is gone forever. And at a safe remove from the danger, some are now trying to cast doubt upon the decision to liberate Iraq. The ability to criticize is one of the great strengths of our democracy. But those who do so have an obligation to answer this question: How could any responsible leader have ignored the Iraqi threat?"