A new Defence Secretary is the minimum precondition for a policy debate that is more meaningful. If not, the United States could find itself in a surreal situation where it has removed one dangerous tyrant with ambitions to hold weapons of mass destruction yet stood by while another in a neighbouring state triumphs where Saddam Hussein failed.

That Mr Rumsfeld must leave to allow someone else - in ideal circumstances, the Democrat Senator Joseph Lieberman - to make the case for threatening to exercise American power is both painful and paradoxical. Yet there it is.

Lieberman is a smart guy, and he probably knows there will be a primary. My guess is that there's a strategy here. Lieberman is setting himself up to run as an independent should he be embarrassed at the convention. Everyone including the Lamont campaign assumed that Lamont would need to petition to get on the ballot, though there was an outside shot of him getting the support of the 15% of delegates at the May 20 convention required to do so. At this point, that threshold looks quite doable, and should Lamont gain an embarrassing number of delegates, Lieberman may just jump out of the party altogether and prep himself for an independent run. He'll need a lot of ballot signatures to get on the ballot, and he hasn't really talked to his base for a long time, so starting early is important for him politically speaking.