Kevin Drum wrote the post that I've been meaning to write, which is that if Bush carries through with his stated budget promises, which include the Medicare bill already passed, holding spending to 4% per year, and making the tax cuts "permanent," the only way he can come close to "cutting the deficit in half in 5 years" is if Bill Gates, Warren Buffett, and George Soros all donate the bulk of their fortunest to the federal government. At best, without AMT reform, the deficit will be cut from $480 to $440 billion dollars.
Kevin's analysis also ignores likely increased Iraq expenditures and various assorted tax giveaways Bush may propose.