For those that don't know how this works, here's a short overview. Every 10 years, the government sets out to count every person in the country (the census). The numbers that the census turn up play a large part in the government at various levels. Perhaps the biggest, most visible way, is the number of representatives that each state sends to the US House. Since 1913 (not counting the one time Alaska/Hawaii exception) this number has been set at 435. Leaving out the complex math that goes into it, after each census it is determined how many house representatives each state gets (although each state is guaranteed one) based on the number of people there.
That's where it gets interesting for Wisconsin. We will be losing one seat. Considering the fact that every congressional district has to include the exact same number of people at the time of redistricting, it seems likely that the seat that will be lost will be in SE Wisconsin. Logic would dictate that the current 4th district would be absorbed by the 1st and 5th to some degree. Of course, we won't know for some time yet what sort of cartography contortions will be done to give Wisconsin it's 7 seats, but with the Republicans in control of the Governor's Mansion, State Assembly, and State Senate, you can be sure that the balance that we currently have in SE Wisconsin will change.
But what to do with that extra representative? Someone is losing his/her job. I'm far from a scholar when it comes to redistricting, but if it were me, the person that is representing the district that is eliminated would be out of a job. Some people, I'm sure, would argue that the most junior representative would be tossed. And that's the ballgame folks. Either very liberal Gwen Moore (WI-4) is out if the 4th really is dumped or either Sean Duffy or Reid Ribble (both won their first terms on Tuesday) will be ousted. It is possible, although quite unlikely, that a current representative would voluntarily retire to free up the seat. The only candidates that I see doing that are James Sensenbrenner (WI-5) and possibly Tom Petri (WI-6). Tammy Baldwin (WI-2) is such an entrenched part of the Madison liberal establishment that I don't see her going anywhere. Ron Kind (WI-3) may also consider it. Had the winds of change not been blowing so hard the other way, Kind would have considered a run for governor this year.
As much as I hate to say it, the wild card here is Paul Ryan (WI-1). He is a rising star in Republican politics and is poised to become a leader in the new Republican majority. However, despite his assurances to the contrary, if the tide continues to turn against the Democrats, he will be given the full court press by the RNC and prominent Republicans to change his mind. A one year break to put his ducks in a row before a big time campaign might be enough to get him to at least consider it.
It will be a very interesting time. How are the lines drawn? Who will be looking for a new job? Will someone "take one for the team" so another colleague can keep their job? Only time will tell.