The slippage in Obama's "days, not weeks" promise

James Fallows, soberly upbraiding Obama for blowing off Congress in his prosecution of the isn't-war in Libya, repeats a quasi-misconception that in an odd way illustrates his point.  Arguing that Obama set himself up for Congressional rebuke by not seeking Congressional buy-in from the start, he writes:

This was a problem foreseeable from the very start* -- more than three months ago, when we were told that this would be a campaign of "days, not weeks."

Obama did not quite say that -- though there is some ambiguity in reports of what he did say on the two occasions when he used the phrase "days, not weeks."

First, on March 18, ABC's Jake Tapper relayed second hand what Obama reputedly said behind closed doors to Members of Congress.  The headline of the short item misrepresents the body content: