She wasn't on the ballot last week, but Tuesday was a bad night for Sen. Olympia Snowe. With conservative insurgents taking on GOP incumbents across the country, Snowe is a prime target for a Tea Party challenge in 2012. To fend off such a challenge, Snowe might have pointed to the failed candidacy of Christine O'Donnell in Delaware and warned Tea Party activists that if they want to hand a Republican seat to the Democrats the best way to do it would be to replace her on the ballot. But that argument lost some of its currency when Tea Party...