When historians come to write the history of American politics in the early 21st century, they will have far less to say about the ostensible points of difference between the two major parties – the war in Iraq, taxes on the rich, the health care “crisis,” the health of the economy – than they will about the style and tone of election campaigning. After all, that’s what the candidates themselves prefer to talk about.

We are well and truly into the era of the meta-election, in which the only issue of the campaign that matters is how each side is conducting the campaign – and whether one can make its own charges of dirty play stick against the other while continuing to play as dirty as they can themselves.