According to this nifty table I found at Foreign Policy.com, 21 separate rationales to support an invasion of Iraq were publicly expressed between September '01 and October '02 (which adds, btw, to the already stellar credibility of the Downing Street Memos). You know what's missing from the table? The rationale a great many liberals believed was the actual one.
Yes, according to George W. Bush, that blood being spilled is for oil after all.
I suspect this has less to do with a desire to come clean about the dishonest case he made prior to the invasion as it does with a desire to capitalize on people's frustration with the price they are paying for gasoline.
If every vote was an I.Q. test, everyone who voted for Bush failed. He's a fuck-up of massive proportion.