People who've been following Attorneygate have by now heard the talk radio types predictably mewling 'But Cliiiiiinton!'. And, yes, Clinton did fire all 93 US Attorneys upon taking office. So did Reagan, and Bush the Smarter. Shrub actually kept a few appointees from the previous administration. That's SOP. The crop is renewed every time a new President takes office. And, yes, these attorneys serve at the pleasure of the President, and can be fired mid-term if there is cause. It's happened twice since 1981.
While they aren't members of the judicial branch, these men and women are like Supreme Court justices - who are effectively also appointed by the President - in that they can only do their jobs effectively if they have job security - at least enough that they can reach the end of their terms without worrying about stepping on executive toes. The stated tasks set before them are enough to occupy them already; they're not there to help the President influence elections. Or to let powerful and corrupt friends off the hook. Attempts to turn them into such tools are, without resort to hyperbole, an affront to democracy and an assault on justice, even without then lying to Congress and everyone else about it, or simply and premeditatively rewriting inconvenient rules that might make your malfeasance more difficult. Subverting the mechanism of justice - faltering and rusty as it may sometimes appear to be - so brazenly, and to such venal ends, betrays a corruption without precedent in any administration.