If there was ever a case of why Democrats need to try to run candidates in every district, WI-06 is a lulu. Tom Petri has held the district since a 1979 special election, but is about to face his stiffest primary challenge yet in the form of state senate majority whip Glenn Grothman, one of the craziest state legislators in the nation. This is a guy who thinks money is more important for men than women and doesn't believe workers should get weekends off. As of now, there is no Democratic challenger here--presumably because Petri has a hammer lock on a seat he's held since 1979. It's too bad, because if Grothman were to win, he could give the NRCC a lot of heartburn for some years to come--much like Michele Bachmann did in neighboring Minnesota.
For those who don't know, WI-06 includes some exurban and rural territory near Milwaukee, Madison and Green Bay. Its PVI of R+5 makes it a swing district on paper, and it has occasionally voted for Democratic presidential candidates. Clinton carried it twice, and Obama carried it in 2008. While it became slightly redder on paper, Romney only carried it 53-46 in 2012. However, it is solidly Republican downballot, and has been in GOP hands for all but two years since 1939. That being said, though, Grothman is way, way, way too conservative for this district. This is a guy who wanted to classify single parents as potential child abusers, for God's sake. This district is just purple enough that if Grothman were to win here, he wouldn't be able to breathe easy. The parallels with Bachmann are undeniable. She was way too extreme even for a district that is easily the reddest district in Minnesota--and as a result, the NRCC had to spend a lot of money defending a district that they should have never had to worry about on paper. A Democrat could also play up the fact that Grothman doesn't live in the district, even though Grothman's state senate district includes much of the southeastern portion of the congressional district.
The thing that should really frustrate the GOP? Grothman's home in West Bend is located in WI-05, a district much more to the liking of a teabagger from central casting like Grothman. Jim Sensenbrenner is 70 years old, and has at most three more terms left. If Grothman had just been more patient, he could have run in WI-05 and pretty much turn it into a sinecure. But instead, he decides to make a run in a district that could give his fellow Republicans headaches for awhile. And that suits us just fine. After all, if they have to pour money into this district, it's less money they'd be able to spend helping defend Sean Duffy and Paul Ryan.