The NY Times says that Bush is "resigned" to hearings, and quotes him as saying:
"There will be a lot of hearings to talk about that, but that's good for democracy. Just so long as the hearings, as they explore whether or not I had the prerogative to make the decision I make, doesn't tell the enemy what we're doing. See, that's the danger.''
I suspect that "tell[ing] the enemy what we're doing" actually means "exploring whether the program was restricted to wiretapping suspected terrorists, as opposed to others of interest to the Administration."