As for the rest of the state, the Republicans have two major liabilities: the 7th district and the 1st district. They probably have the votes to shore up one of these districts, but not both. Their choice is between siphoning off Republican areas from safe seats (Districts 2, 3, 4, 6, 8, and 11) and sending them north to the first, or south to the seventh.
The seventh district is probably the Republicans’ better bet to hold safely in the 2012-2020 cycles. Yes, the GOP was able to flip the first district this past cycle, but that was largely a combination of the popular Democratic incumbent not seeking reelection and a wave year boosting the Republican candidate to victory in the open race. In a typical year, there are more Democrats than Republicans in the first, and as soon as the Dems find another Bart Stupak – i.e. a Blue Dog with social conservative credibility who runs ahead of the rest of the Democratic ticket – the seat should revert to the Democrats.
Geographically, the seventh district won’t be easy to stack with Republicans. The district is bounded by state boundaries to the south and Democratic-leaning areas in any other direction the Republicans might try to expand it: Ann Arbor to the east, Lansing to the north, and Kalamazoo to the west. How exactly the Republicans will try to stack it will depend on how much population the district will need to add. If the district needs to lose population or doesn’t need to add much, they can probably move GOP-leaning bits and pieces from the 3rd, 6th, 8th, 11th, and even the 15th districts to shore up their numbers in the 7th without giving too much away in the other districts.