NOW THAT HE'S BACK IN the elections business, Karl Rove has a huge task on his hands: assuring strong Republican voter turnout. At the moment, Republicans are in a funk. And their dejected mood may presage a low turnout in the midterm election on November 7. Should a large number of Republican voters sit this one out, Republicans could lose control of one or both houses of Congress. It's when Republicans are either inspired or angry that they show up in large numbers and win elections. So Rove, along with Republican national chairman Ken Mehlman, has the job of shaping...