It’s the new strategy of congressional leftists in league with anti-war groups:

Top House Democrats, working in concert with anti-war groups … will pursue a slow-bleed strategy designed to gradually limit the administration’s options.
Led by Rep. John P. Murtha, D-Pa., and supported by several well-funded anti-war groups, the coalition’s goal is to limit or sharply reduce the number of U.S. troops available for the Iraq conflict, rather than to openly cut off funding for the war itself.
The legislative strategy will be supplemented by a multimillion-dollar TV ad campaign designed to pressure vulnerable GOP incumbents into breaking with President Bush and forcing the administration to admit that the war is politically unsustainable.