Why doesn't George Bush just ASK Karl Rove if he did it?

What is this BS about Bush now waiting for the investigation to complete so that he doesn't have to judge Rove based on media reports. For a president who doesn't read the media, that shouldn't be a problem. Simply pick up the phone, call Karl, and get his butt in your office and ASK him if he was the leaker or not.

Either Bush has done this and knows Rove is the leaker, and in which case Bush lied when he said he would fire the leaker - not to mention, that would mean Bush has been tolerating a security risk, and possible criminal, on his staff for two years now - or Bush has not called Rove in and asked him, which begs the question why not?

Why won't Bush just ask Rove if he did it?