Go off the deep end does not only mean 'get angry'; it also means 'act extremely; go too far', and I think that is what Bill means here: The Bush administration has gone too far. Off means 'beyond': beyond the deepest (most extreme) part. As with so much = in the same way as in many other cases.
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Liveinjapan"Go off the deep end" means to get very angry about something or lose control of yourself.No. That's just one definition. The other definition is the one you want: to do something crazy; to act recklessly; to go too far (figuratively)
Liveinjapanhow does the "off" work here?S
CalifJimthe etymology at http://www.englishdaily626.com/slang.php?055
CalifJimThe reference is to jumping off the edge of the deep end of a swimming pool, plunging into the deepest water.Got it! Thanks, CJ.