Bush may be vulnerable to substantive criticism of his personal capabilities and his policies and motivation. There might be a rational and convincing argument to be made for voting for "anyone but Bush".
But we won't find out in 2004. Michael Moore has done more than any other single man to guarantee that. Someone on the left may voice such an argument, but he'll be drowned out by rabid LL jihadists as they stridently deliver a message tailor-made to alienate the broad electorate in style of presentation, in attitude, in substance, and in underlying message. Moore holds a locus of extreme political positions, and most Americans will consider at least one of them to be utterly odious. (For instance, Moore strongly favors gun control, but Americans actually own more guns per capita than do the citizens of any other nation.)
It is rare for a political faction to be blessed with an opponent who is so charismatic to his fanatical supporters, so repulsive to non-supporters, and so vulnerable to criticism and caricature. I can't think of a high-profile leftist I'd rather have "at the centre of things" than Michael Muqtada al-Moore.
And THAT is why I read den Beste