Another statistic could be cited: Obama carried only 209 congressional districts, while Mitt Romney carried 226. While capturing all 17 Obama House Republican seats would give Democrats a 218-217 majority, as a practical matter (and because Republicans have a good shot at winning some current Democratic seats) Democrats are going to have to capture at least some Romney seats. If Obama's job approval continues to be under its November 2012 levels, as it is now, and if voters continue to vote straight tickets, as they have done increasingly in the past 20 years, that's going to be difficult.
Of course there is still a chance Democrats could win back the majority. Circumstances could change. But America's current demography — with Democratic voters clustered in central cities, certain suburbs and university towns, and Republican voters spread more evenly around the country — the House is an uphill climb for the Democrats. In the last 20 years they've won House majorities only when there is an unpopular Republican president. Whatever the results of the government shutdown battle, that won't be the case in 2014.