We're guessing this isn't the only time that you'll be hearing this on the stump between now and November, especially given how much the president appeared to enjoy delivering it.
Here's the quote (via Politico):
"I mean, he’s changing up so much and backtracking and sidestepping, we’ve got to name this condition that he’s going through. I think it’s called 'Romnesia,'" Obama said to laughter and cheers at George Mason University in Fairfax, Va., where he spoke to a morning rally of 8,000. "That’s what it’s called. I think that’s what he’s going through."
Clearly enjoying himself, nearly giggling as he spoke, Obama continued: "Now, I’m not a medical doctor, but I do want to go over some of the symptoms with you — because I want to make sure nobody else catches it."
The base-pleasing laugh line comes one day after the president stopped in New York City to appear on the Daily Show, and to give stand-up comedy a try at the annual Alfred E. Smith Memorial Foundation Dinner.
Here's the video from today's rally, where you can hear the rest of Obama's "You may have Romnesia if..." bit: [Update: It looks like the president didn't coin the term himself, instead finding it on the Web.]