Republicans have been slipping in the polls since their mishandling of the debt ceiling debate (here and here) and now a poll shows that this could translate into losses in the House. A new Gallup poll shows Democrats leading Republicans 51 percent to 44 percent in the generic Congressional ballot.
This is hardly enough to predict that the Democrats will retake the House. Momentum can, and probably will, shift more times between now and the 2012 election. Republicans might withstand these numbers due to controlling the redistricting process. Having Democrats more concentrated in urban areas makes it easier to make a smaller number of districts which have huge Democratic majorities, so even if Democrats win over half the popular vote they could wind up with less than half of the Congressional seats. (This is exaggerated even more in the Senate where sparsely populated Republican states receive the same number of Senators as in heavily populated Democratic states).
Democrats will probably need to expand this lead in the generic ballot to repeat their successes in 2006 and 2008:
… the Democratic advantage is not as large as those they enjoyed in the 2006 and 2008 congressional election cycles — each of which produced a Democratic majority in Congress. The Democrats averaged a 10-point lead over Republicans among registered voters in the year prior to the 2008 elections and an 11-point advantage leading up to the 2006 elections, with individual polls showing them ahead by as much as 23 points.
Democrats have a better chance to win if they can highlight both the fiscal irresponsibility of the GOP along with Republican votes which would destroy the Medicare program. The best chance for Democrats will be if the Tea Party remains active, as another recent Gallup poll shows antipathy towards the Tea Party growing. Running more Tea Party candidates could weaken the Republicans, and even being associated with the Tea Party could be damaging to Republicans outside of extremely far right areas.