"What did the President know and when did he know it?", a question given him to ask by his counsel and former campaign manager, future U.S. Senator Fred Thompson. http://en.wikipedia.org/wiki/Howard_Baker
Mark Steyn's article at National Review Online draws a familiar parallel
“This isn’t the Tony Rezko I knew,” said the senator, in what’s becoming a standard formulation. Likewise, this wasn’t the Jeremiah Wright he knew. And these are guys he’s known for 20 years.
Perhaps we ought to resurrect Fred Thompson's question and direct it (in a somewhat modifed form) to Sen. Obama
"What did the Presidential candidate know and when did he know it?