I think one of the big reasons that the November elections went the way they did, is that the people in power got so cocky. They started breaking too many laws and started getting caught, a lot.
Who prosecutes those cases? Often it is the U.S. attorney's office. So, if Bush wants to send a message, to U.S. Attorneys, to "back off", or stop some prosecutions entirely, what does he do?
Read this, it could be nothing, but it could be something.
Here is Senator Feinstein's letter.