It's classic Rove, as Josh Green explains here. Money quote:
The closest race of Rove’s career the 1994 election for chief justice of the Alabama Supreme Court in which Rove’s candidate actually trailed the morning after the election hinged on the issue of voter fraud. As I discovered from Rove’s own staff while doing a profile of him in 2004, Rove himself pushed the voter fraud issue aggressively and ultimately won the race.
Of course Rove rigged the U.S. Attorneys system for partisan reasons. That's his job, as far as Bush is concerned. And please don't believe for a second that Bush isn't up to his neck in this as well.