What are your expectations for this country and politics if the Republicans win back the House?
First, I think Obama will be impeached.
Second, in conditions where unemployment remains consistently high, as most forecasts expect, I think Obama's chances for reelection might actually benefit from a GOP takeover of the House. With control of the House Republicans won't be able to use every poor economic nugget as a bludgeon against Obama as effectively, and Republicans will actually have some responsibility for a slow recovery.
I think a GOP takeover will allow Obama to once again be able to demonstrate that the Republicans are totally bankrupt on having any new ideas apart from the Bush agenda, that they care nothing for the actual governance of the country, that they have no real solutions for solving the most pressing of America's concerns, and not only that but they'll remain the Party of No in defeating centrist proposals such as the deficit commission, which will likely release a spending cut heavy proposal. Once Obama can highlight their hypocrisy on the deficit, they'll lose it as a tool to attack him with. Despite a slow recovery the deficit will naturally come down if GDP continues to improve and as the Iraq war and possibly the Afghan war winds down, which out to begin in late 2011 to come early enough for the 2012 election.
Future legislative wins will also be hard to come by, I expect he'll win no big victories, but I think he'll get a few Clinton sized wins out of the congress. I think he'll be able to force a somewhat better long-term budgetary outlook through the 112th congress, not without a lot of Republican teeth-gnashing, and I think he may win the repeal, of DADT, but those may be his biggest wins. I think in the longer term he may get more, such as immigration reform, but not in the 112th. If the Democrats ever retake the chamber he may get an energy bill passed, but nothing huge.