You might be sitting there thinking "Hey, didn't I see these numbers before?" and, if so, you're right... PPP polled Wisconsin's 2012 Senate race in December when the specter of a Herb Kohl retirement seemed to be looming larger than now, and their new round of polling (obviously more focused on the standoff over collective bargaining rights and the prospect of recalling Scott Walker) finds very little has changed in that race amidst the rest of the state's upheaval.
The most notable changes are that they've swapped in ex-Rep. (and 2010 GOP gubernatorial primary loser) Mark Neumann in place of Tommy Thompson, only to find he does no better than the other options... and they note a big drop in Paul Ryan's favorables, in the period since his SOTU response (the place where Republican rising stars go to die), down to 36/35 from a previous 38/30. Herb Kohl's approval is 50/30, while newbie Ron Johnson's approval (32/28) is worse than the favorables of the guy he just beat, Russ Feingold (51/39). What a difference a little presidential-year-electorate makes!