There was a lot of chatter back when the US Attorney scandal was going on about how these guys served at the pleasure of the President, so there was nothing wrong with firing a bunch of them for potentially partisan reasons. Across the river, in New Jersey, there is a heated battle for Governor. The Republican, Chris Christie, was a US Attorney with ties to the scandal. This included discussion with Karl Rove about a run for Governor. Understandably, Corzine (the Democrat) has seized upon this as a sign that Christie was doing nefarious things.
I don’t know if Christie did anything untoward, but the fact that he survived the purge of US Attorneys creates the impression that he is a bought and paid-for operative of BushCo. That is why the politicization of this office is wrong. It creates an environment of potentially false allegiances. It casts doubt on the service of people all over the country that probably did nothing wrong, but were either fired or retained for reasons unknown, but oft speculated.