The larger plan
Chris Bower's has a good post today suggesting that our ultimate victory will depend not on defeating any one individual Republican but in painting a frame around the Republicans based on a "Culture of Corruption."
Defeating Karl Rove, Rick Santorum, Tom DeLay or George W. Bush is not our primary concern here. Our concern is to make it clear to the electorate that Republicans=Corruption and Democrats=Reform. If we succeed then the defeat of Rove, DeLay, et. al will follow in due course.
It is to our advantage that Bush doesn't fire Rove or that Rove resign. He is the poster child for the "Republican Culture of Corruption" and we should use him to our full advantage.
The calls for Rove's resignation should be pro forma, but we should not devote a lot of time to them. Instead, we should make it clear that if Bush decides that keep a rat like Rove close by then that just tells us something important about Bush's character. If, by keeping Rove, Bush is comfortable with an image of political expediency over serving the national interest then that is just fine by us. It is his right to swim in whatever swamp he wants to swim.
It is our job to point out what kind of swamp he is swimming in.