Senate Minority Leader Harry Reid's mad. Reid Calls Bush a 'Loser'. And it looks as if it has something to do with this:
Two weeks ago, Reid essentially called Bush a liar when Vice President Cheney said he agreed with Senate Republicans about changing the filibuster rule. Reid said that violated a commitment Bush had made to stay out of the fight. Reid said that it “appears he was not being honest.”
I missed that comment when it happened, although I inferred it (cf. The Telling Detail).
Actually, it's much worse than mere lying. Bush lies to us all the time, and few professional politicians take it personally, more's the pity. Politicians lie, and others live with it. But what this story is about is breaking your word, delivered eye-to-eye in private. Senators see that as much worse than lying to the public.