Republicans at risk of losing the House

Republicans at risk of losing the House

September 20th, 2012, 10:00am by Sam Wang


Conditions through August showed a 2% lead on the generic Congressional ballot for Democrats. As of September 20th, in the wake of the Democratic convention, the lead has widened to 4.0 +/- 2.0%. Although it has yet to be appreciated by pundits, this could well translate to a November loss of the House of Representatives by Republicans. Based on the generic Congressional ballot, the probability of a Democratic takeover is 74% with a median 16-seat majority. Whichever party is in control, the seat margin is headed for being narrower than the current Congress. Like any probability in the 20-80% range, this is a knife-edge situation. This picture may change over the coming six weeks as more information, especially district-level polls, becomes available.

As seen in recent articles in Politico and U.S. News, few pundits think the Democrats will re-take the House. However, analysis of a leading indicator suggests to me that transfer of control is a distinct possibility.


Predicting the House outcome is challenging. First, there is the basic problem that we have to estimate how far opinion will move between now and November. On top of that, there is uncertainty in knowing how the polling measurement – generic Congressional ballot preference – translates to a seat outcome.


Another approach would be to use district-by-district polls and ratings. An estimate like that can be seen from our data partner, Their House outlook shows retained GOP control, and RealClearPolitics implies the same. However, many of those polls are weeks or months old. My estimate today suggests that in the coming weeks, we might look for district polls to move in the Democrats’ direction. This is also an opportunity for a detailed analytical approach, as taken elsewhere, to shine.


In 2010, the national Congressional vote was a big 6.6% margin of popular vote win for the Republicans. That outcome was very close to the pre-election R+7% polling median (but 8 points less than the final Gallup poll of R+15%). So the generic Congressional preference poll, aggregated across pollsters, can give some sense of where the vote will go.


In 2012, the picture looks very different from 2010. Congressional voter sentiment before Labor Day is often movable (see 2008 and 2004 history). But we are now entering the high season, so some sense of the outcome is starting to emerge.


In summer polls leading up to the 2012 conventions, Republicans were behindDemocrats by a median of 2%, a 9-point swing from 2010. Consequently, many seats won in that Republican wave are now at risk, as I pointed out in my previous House outlook. To put it another way, midterm election conditions (as in 2010) work against incumbent Presidents; the pendulum has now swung back.


In post-convention polls, Democrats got a big bounce that peaked at D+6% and now appears to be subsiding. It is a good thing for the Republicans that the election was not last week. The most recent polls (Sept. 7-17) indicate a median lead of D+4.0+/-2.0% (+/- estimated SEM, n=7 different pollsters). (Note that the HuffPost smoothing software uses a different algorithm.) This 11-point swing from 2010, if it were to hold, would lead to big Democratic gains in the House.

As I pointed out two weeks ago, the eventual national D-minus-R House popular vote share is strongly predictive of the corresponding margin of House seats. Here is a graph based on data from 2000-2010 House elections.

National House seat margin vs. vote margin, 2000-2010

It shows that each 1.0% of popular-vote margin translates to a 6.0-seat advantage. This plot shows no long-term advantage* for either side: a nearly-tied popular vote would translate to a nearly-tied House (x-intercept = -0.3 +/- 1.1%). Individual data points deviate from the fit line by 7 to 17 seats in either direction.


However, there is a known advantage to incumbency, which I estimate as being worth an equivalent of 1.3 +/- 1.0% of popular vote. This is smaller than a recent estimate**. In other words, on average a national win of D+1.3% is required for the House to change hands.


Next, let us translate the generic Congressional ballot to estimate House seat outcomes. Applying the Wisdom-of-Pollster-Crowds principle that has served so well in Presidential and Senate races, we will use the poll median to approximate the actual popular preference.


The HuffPost graph above includes telephone polls (i.e. not robopoll or Internet), but that is strictly for purposes of clear display. Using all polls and median-based statistics to address issues of outlier data gives the median of D+4.0% that I gave. That translates to a narrow 16-seat Democratic majority in an election held today.


This would be an unusual outcome. It would involve a Democratic net gain of over 30 seats, much more than the typical gain for a re-elected president’s party. But 2010 was also an exceptional wave year for the Republicans. Again, think of the pendulum. In any event, this is what the numbers are currently telling us.

The principal caveat. The main issue with this analysis is that it does not use district-level data. In the coming weeks, those surveys will become more abundant. In 2008, district polls did a very good job of estimating the outcome – on Election Eve. Six weeks out, the generic ballot preference is the week-to-week indicator that is available.


Where things could go in the next seven weeks. Assume a +/-4% opinion shift between now and November, and this leads to a popular vote prediction ofD+0% to D+8% (1 sigma). This gives a Democratic takeover probability of 74%, approximately three out of four.***


It should be noted that current conditions emphasize the post-convention bounce, which could be transient. Conversely, if the Democratic lead increases, that would take House control out of the knife-edge territory that I defined previously. For now, a smart use of campaign donations is to donate to the DCCC through this ActBlue page, or the GOP through Crossroads GPS.




Are you interested in a specific race? For tracking specific districts, watch the aggregators such as our data source (HuffPost/ and RealClearPolitics. Considering the current 11-point swing, any race that was won in 2010 by a Republican by less than 15% should be considered competitive, and worth getting involved if you are a Democrat or Republican currently on the sidelines. I myself find this surprising, but that’s what the arithmetic is saying.





*We can ask whether redistricting should affect the x-intercept, i.e. give one side a structural advantage. Often the goal of redistricting is to protect specific incumbents. This is different from the goal of altering the total number of seats expected by either side. Indeed, maximizing one goal can work against the other by collecting partisan advantage into a few incumbents’ districts, at which point even a little swing can flip the outcome in the other districts. This is a complex subject, and to my knowledge it is not proved that gerrymandering leads to a global structural advantage.

**A four-factor model at FiveThirtyEight has led to a meme propagating through the political blogosphere that there is a 3-4 point structural advantage for the Republicans. However, that estimate is less precise than it appears.

When doing multiparameter regression, it is important to quantify uncertainty, as well as avoid fitting to noise. Here, two quality checks are to (i) make sure the the uncertainty does not blow up when all the extra factors are added, and (ii) make sure a large fraction of the 7-17-seat residual can be accounted for by each added factor. After playing around with the four-factor analysis, I have concluded that it is likely to fail these criteria. The consequence is low confidence in estimating the structural advantage. A simpler model using only this-year’s-national-vote and last-Congress’s-seats (i.e. two factors) applied to 1996-2010 data has less of this problem, and indicates a structural advantage to Republicans in 2012 of 1.3 +/- 1.0%.

***This is in marked contrast to the InTrade price of 0.17, which corresponds to an imputed market opinion-driven probability of 17%. As I have previously pointed out, InTrade market opinion is often quantitatively wrong. In this case it might even be getting the direction (i.e. <50% or >50%) wrong.

Tags: 2012 Election · House









"I'm just trying to make a way out of no way, for my people" -Modejeska Monteith Simpkins









Original Post

Just last week I sent an email to the President and the DNC suggesting that they needed to mount a campaign that was not only directed towards getting the President re-elected ... but that a very strong initiative should be made to convince ALL voters (even the ones who won't vote for him!!) to vote for the local Democrats in their region ... to give the President the Congress he needs to actually get things done!! 


In the note to the President I suggested that I thought that the DNC sucked at determining which campaigns they should and should not support more than others (as evidenced by allowing a Republican to take over Ted Kennedy's seat after his death ... which was just stupid and proved nobody was obviously paying attention to what they should have been paying attention to to let that happen! ).


The American voting public has it really bad when it comes to just voting for their Congressional members who they're always voted for .. without giving it any thought!!  In 2010, here in Texas ... two DEAD people were voted for and elected because their names were still on the ballot and nobody knew any better.    Now, I ask you ... how sad is that?? 


But .. people need to be convinced that a President with an unfavorable Congress is 4 years of wasted time .. for everyone!!  The past 4 years should have PROVEN that ... beyond a shadow of a doubt ... even for the politically-challenged!!  Of which there are waaaayyy too many!   


And, as we saw with the health care debate ... just having a majority doesn't mean a President can get his legislation passed.  It was so-called "Democrats" that blocked the public option from being included.  A Conservative Democrat is just another name for a Republican .... in every way that counts!!


So people need to be VERY conscious of who they are voting into those Congressional seats!!  And, at least for this political time and election,  the more Democrats that get in, the better off we'll be!!

Good for you ER and you are on point with what you are saying. I may send one too, we all should.  


I may express those point via a petition that can be sent to the President and the DNC.  


If republicans win in November, I do believe that the right and the racist in America are going to do everything in their power to make it even harder to Black people and minorities and Liberals in this country.  It will not be pretty for Black people because I can't see many Black people being prepared to start taking crap that republicans put in their base voter's heads.  I also believe that if republicans win in November, it will be the beginning of the end of America as we know it.

You know, Sunnubian ... I haven't even tried to imagine what America would look like if Republicans were to win in November!!


I don't think there would be much of a problem from the racists - after all, they'd be happy and there'd be no need for them to act a fool any longer!!


However ... soooooo many people would be negatively affected.  What happens to society as a whole once millions of people stop being able to receive assistance - welfare and food stamps ... once children start getting kicked out of Head Start and public school teachers lose their jobs, en masse ... and states stop being able to afford to pay police and firefighters.  


They want to gut Social Security and Medicare .. and Medicaid ... so what happens to all old people once they get sick and have no where to go for treatment??  When they start dying... I can't imagine the Republicans caring enough to do anything about it!!


Over the next four years, so many people would end up truly suffering ... and the rich would not stop trying to make themselves richer in order to help them.    It would be horrible.  And I hope and pray that we don't have to see it up front and personal, live and in living color!!

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