The Obama approval rating is one point higher than the Romney favorable rating, and the sample is R+2 in a state that is at least even.
Paul Ryan may have an effect for now - an unusually-high one for a VP nominee. Wisconsin voters will soon get to know him as they never knew him before, which might not be such a great thing for Romney. Joe Biden isn't popular in Wisconsin.
Accepted with the caveat that PPP may be bending over backwards to let Republicans think that they have a chance in Wisconsin.