George Will fails to see the gorilla sitting on his face:

Kerry says he would not rule out pre-emptive military action, but Bush probably exhausted his ability to take such action by doing so against a nation that lacked the attribute that could justify it — possession of weapons of mass destruction by a regime likely to use them.  Yes, the world is better off because Bush rid Iraq of the regime that filled the mass graves, but he does not argue that human rights horrors justify pre-emptive war.

The first crisis of the next presidential term probably will be Iran's approaching possession of nuclear weapons.  Bush's policy already is Kerryesque: ask "the world" to help.  It is not working.

It's not working precisely because Bush has "exhausted his ability to take such action" by shredding America's credibility as a moral leader.  That George Will, the most priggish and desperately over-intellectual of all conservative pundits, cannot recognize this – even when the logic of it is glaringly apparent in his own writing – is remarkable.  Furthermore, how can we expect the world to listen to our entreaties to unite behind a cause of common concern after we so blatantly rejected their entreaties to us to respect the rule of law?  That the Kerry campaign is rejecting "negativity" is maddening in this respect – Bush deserves to be pilloried for his profoundly unethical, unlawful, and disastrous actions as president.  Our credibility on the world stage demands not only that we replace him, but that we acknowledge the mistakes that have been made as a result of his incompetence.

UPDATE: Here's a more sophisticated argument for new leadership.