Sens. John KerryJohn Forbes KerryKerry to campaign with Biden in New Hampshire Kerry endorses Biden in 2020 race: He 'can beat Donald Trump' New Hampshire parochialism, not whiteness, bedevils Democrats MORE (D-Mass.) and Bob Casey (D-Pa.) urged the State Department on Wednesday to stop using Blackwater contractors to provide security for U.S. diplomats in Iraq.

The senators' push comes on the same day an internal State Department report found that the company may lose its license to operate in Iraq. The contractor has come under heavy scrutiny for its aggressive tactics. Five of its guards face manslaughter charges connected with the 2007 shooting deaths of 17 Iraqi civilians.

"The era of Blackwater must finally end," said Kerry, who will serve as the Senate Foreign Relations Committee chairman in the next Congress. "The incoming Obama Administration can proceed with the knowledge that even the Bush Administration acknowledges that outsourcing overseas security to private firms like Blackwater is a mistake."

The letter that Kerry and Casey sent to Secretary of State Condoleezza Rice is below.

Dear Madam Secretary:

We are writing in response to recent news reports that Blackwater Worldwide (