Get The Mercs Out First, a Variety of Arguments For

• They are a moral hazard for the Pentagon.  Corporations have far different rules than the military, and are obligated to follow illegal orders.
• They indicate of a lack of US support. 
• The use of mercenaries by the King of England was hated by Americans.  In the words of U-S-History.com "Hessians who remained in the British employ were hated and feared by the Americans, and the fact that George III had chosen to employ foreign mercenaries stirred up much anger among the colonists."
• They are, in many cases, individually morally repugnant. 
• They encourage defection from military service.  They pay often twice as much, sometimes more than four times as much as the most senior enlisted personnel.
• They cost far more money. 
• They are used to hide the true US presence in Iraq.  If the number of contractors were even known, it might be clear that as US forces step down, soldiers for hire are stepping up.
• There's nothing that they can do that the uniformed military can't.