They are pouring their resources into making folks think that:
a. Saddam had no WMDs
b. He was not supporting al Queda.
If it can be shown that they knew that this threat was real against Americans, and they knowingly lied about it for political gain (aiding and abbetting the enemy in the process) then they will be well and truly screwed come election time.
The fact that they were being partisan will mostly inflame partisans of the other party, its just a minor irritation to the middle-of-the-road folks, who generalize that "all politicians are that way". What will really reasonate is who was actually lying to the public (playing us for fools). It will be worse for Democrats if they are caught, because it will have been life-threatening treason, as opposed to just butt-covering or manipulation.