It seems odd to say this, but conservative commentator Joe Scarborough provided a crystal clear explanation of why the president is moving into dangerous waters. On last night's show he, and his panel, systematically deconstructed the flawed decision making regarding the war in Iraq. I recommend viewing the whole segment (here).
Considering that Scarborough has been a long time supporter of the president, I view this as a hopeful sign that other conservatives will begin to see the light. This is not an issue that can be neatly delineated as a partisan one, all Americans need to see that Bush's failures as a leader will have profound consequences.