ATLANTA — The first outside political group has already started to hammer Georgia Democrat Michelle Nunn using her leaked campaign plan that detailed her strategy and discussed her potential weaknesses as an Atlanta nonprofit executive seeking a seat in the U.S. Senate. Republicans and Democrats agree that even more powerful blows will come later, as GOP nominee David Perdue and the independent Super PACs that support him try to use the Nunn campaign's words against her in a deluge of television attacks Outside groups have already spent more than $8 million on the race, and Perdue, a former corporate CEO, is wealthy enough to finance whatever level of advertising he desires. The question is whether those attacks persuade voters in a contest that will help determine which party controls the Senate for the last year of President Barack Obama's administration.