Taking into account the districts with open seats and the current generic ballot advantage held by Democrats, we would expect to see around 21 Republican-held House seats flip to Democrats this year if conditions are similar to the elections of 1994-2006.
Below, an explanation, as well as details on party identification, approval, House retirements, and the generic ballot. First up, party favorability ratings:
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Since the 2006 elections, Democrats have managed to hang onto a positive party image overall. Republicans have kept digging a hole for themselves. The news is not all good, however. Approval of Democrats in Congress is low, and falling, following a peak just after the 2006 election. It is still higher than the ratings of Republicans in Congress, but that is not much consolation:
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So why does the public still view Democrats favorably? One possibility is the excitement of the primary race. Identification with Democrats ticked up noticeably during the primary season. Democrats now have nearly a 10-point advantage over Republicans in party identification, compared to just about even in 2004:
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The postive views towards Democrats are reflected in the generic ballot question for the House: Democrats have led by about 10 points all year:
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Even in Republican districts, Democrats lead on a named ballot question among the most competitive House districts. This is an improvement over 2006, where, obviously, Republicans won in all these districts. Here, Tier 1 is the 15 or so most competitive Republican-held districts, and Tier 2 is the 15 or so next-most-competitive districts:
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Seeing this, Republican House members ditched their sinking ship this cycle. There’s about 35 vacant house seats, and almost 30 of them are currently Republican-held. This is a lot more than 2004 or 2006 for Republicans, and a little less for Democrats. The graphs below show the pace of retirements for Republicans (left) and Democrats (right), with the 2008 cycle in yellow:
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The Prediction
In the past seven House elections, the number of seats a party gained could be related to the generic ballot polling numbers and the partisan tendencies on a presidential level of each district. Plugging in the current numbers, we get 21 seats changing from Republicans to Democrats (with 95% confidence that the number will be between 14 and 31) while only 1 switches from Democrats to Republicans (95% confidence 0 to 7). This prediction does not attempt to analyze anything on a race-by-race basis. Compared to the prediction I made last fall, it is slightly fewer seats because the generic ballot numbers are slightly worse, although there are now more open Republican seats, which are easier to pick off. Also, don’t forget that Democrats have already picked up three more seats in special elections this cycle.
The following graph lets you watch how the numbers change as the Democrats’ generic ballot advantage changes. The range shown is the range of generic ballot advantage values from recent polls.
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It’s quite possible that the generic ballot will increase as the result of the fundraising advantage Democrats have in House races this year (more on that soon). Of course, the numbers could also go down following a national anti-Democrat smear campaign.
A detailed explanation of these predictions and the fine print is available here.
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Polling numbers can be found at pollingreport.com unless otherwiese noted. This is the third in a series looking at the evolution of the political scene since the 2004 and 2006 elections. The first discussed Bush’s approval ratings. The second looked at the economy and other issues important to the electorate. Tomorrow, FEC willing, a look at fundraising. Cross posted at Open Left and Daily Kos.
