Rush got it right. The Democrats said Bush used the words "imminent threat" in his speech. Example: New York Times columnist Paul Krugman hyperventilated: "The public was told that Saddam posed an imminent threat. If that claim was fraudulent, the selling of the war is arguably the worst scandal in American political history - worse than Watergate, worse than Iran-contra."
The left's complaint was that the Iraq threat was not imminent, the implication being that 'imminent threat' is, in fact, sufficient cause for war.
Thus, contrary to Rush's point today, the addition of "imminent threat" in kerry's speech adds nothing new to current leftist doctrine.
And adding 'imminent threat' is certainly not consistent with the Bush Doctrine. The underlying premise of the Bush Doctrine is that, post-9/11, we cannot afford to wait for threats to become imminent.