Would you agree that the weaponized anthrax spores were probably mailed by Islamic terrorists? And that the terrorists probably got them from Iraq? And that there was probably plenty more where that came from? And that a few kilos worth might have already been smuggled into the US?
This is, at any rate, the assumption that the administration is likely working under. Consequently, the primary reason for delay has been to locate and isolate the anthrax stash and its keepers. And to institute civil defense measures that can effectively deal with a domestic biowarfare attack.
When Bush is confident that this risk has been minimized, we'll move on Saddam. But not a moment before...