This article presents forecasts of national seat swing in the 2014 House and Senate elections based on relatively simple models that incorporate the results of the generic ballot question. The generic ballot question, which has been asked by the Gallup Poll since 1946 and by many other national polls in recent years, provides a way of assessing the mood of the American public in the months leading up to a national election. This question asks a national sample of American voters whether they prefer a Democrat or a Republican for the House of Representatives without providing the names of the candidates.
When included along with a few other predictors in a forecasting model, the generic ballot question produces very accurate predictions of national seat swing in midterm House elections and fairly accurate predictions of national seat swing in midterm Senate elections (Abramowitz Reference Abramowitz2006; Reference Abramowitz2010). Including the generic ballot question results in more accurate predictions of House and Senate seat swing than using other indicators of the national political mood, such as economic trends or presidential approval. In addition, these models produce forecasts more than two months prior to Election Day and do not require any information on individual House or Senate contests.
2014 HOUSE FORECAST: NO WAVE IN SIGHT
The results of the generic ballot forecasting model indicate that the 2014 US House elections are likely to result in minimal change in the current party balance of power. The forecasting model uses only three predictors—the number of seats held by Republicans and Democrats in the House prior to the election, the winning candidate’s margin of victory in the last presidential election, and the relative standing of the two parties on the generic ballot question. Estimates for the model are shown in table 1 based on all 17 midterm elections since the end of World War II.
Table 1 Results of Regression Analysis of House Seat Swing in Midterm Elections
Note: Dependent variable is change in Republican House seats.
Source: Data compiled by author.
The party holding the White House almost always loses House seats in midterm elections. However, the size of those losses varies considerably, and one key factor is how many seats the president’s party is defending. These results indicate that Democratic losses are likely to be limited in 2014 because Democrats are defending only 201 seats this year. In sharp contrast with the situation prior to the 2010 midterm election, very few House Democrats currently represent Republican-leaning districts. As a result, Republican pickup opportunities are likely to be few and far between.
Another regular feature of midterm House elections is that the bigger the winning margin for the president two years earlier, the more seats his party is likely to lose in the midterm election. That is because of the removal of presidential “coattails” in the midterm election. In 2014, however, the effect is likely to be small because President Obama’s margin of victory in 2012 was only 4 percentage points. Obama’s coattails were very short, so Democrats mostly won’t miss their presence this year.
Finally, the results of the generic ballot have a significant influence on House seat swing. The better the performance of Republicans on the generic ballot in early September, the more seats Republicans are likely to gain in November. For every one point of additional margin on the generic ballot, a party can expect to win slightly more than 1.7 additional House seats. Thus, a 10-point generic ballot margin is worth about 17 additional House seats.
The results of the generic ballot question predict House and Senate seat swing more accurately in the late summer and early fall than earlier in the election year. However, based on the number of seats currently held by each party in the House and the results of the 2012 presidential election, we can calculate the expected seat swing in November depending on where the parties stand on the generic ballot in early September. Those results are shown in table 2.
Table 2 Conditional Forecasts of Change in Republican House Seats
Based on the average of generic ballot polls during the past two months, the most likely outcome of the 2014 House elections is a Republican gain of less than five seats. Democrats will need a very substantial lead on the generic ballot, something in the vicinity of 12–14 points, to have a good chance of gaining the 17 House seats needed to regain control of the chamber. At this time, that result appears highly unlikely—no poll in the past year has shown a double-digit Democratic lead on the generic ballot. Moreover, no party holding the White House has gained anywhere near 17 seats in a midterm election in the past century. It seems highly unlikely that 2014 will see such a result. However, it also appears highly unlikely that Republicans will significantly increase the size of their House majority in November. This means that Republican leaders will probably continue to experience difficulty in producing enough votes to pass legislation without Democratic help on issues such as immigration reform that divide House Republicans.
SENATE FORECAST: PARTY CONTROL AT TIPPING POINT
In contrast to the situation in the House elections, party control is clearly up for grabs in the 2014 Senate elections. The main reason why Democrats are at risk of losing control of the Senate in November is not because of public discontent with the Affordable Care Act, continued weakness in the economy, or President Obama’s mediocre approval ratings. All of these issues may have an impact on the Senate elections. But the Democrats’ biggest problem this year is that they were so successful in the 2008 Senate elections. While Barack Obama was capturing the White House in 2008, Democrats gained eight seats in the Senate, winning 20 of the 35 seats at stake.
Now Democrats must defend all of the seats that they won six years ago, including several in states that usually support Republicans. Of the Democratic seats that are up for election this year, seven are in states that were carried by Mitt Romney in 2012 including six that Romney won by a double-digit margin. In contrast, Republicans are only defending one seat in a state that was carried by Obama in 2012—Susan Collins’ seat in Maine.
The values of two of the predictors in our model make it clear that 2014 is likely to be a difficult year for Democrats in the Senate.
A simple model incorporating the results of the generic ballot question allows us to make fairly accurate predictions of seat swing in midterm US Senate elections. This model is very similar to the House forecasting model. The three predictors are the results of the generic congressional ballot question in early September, the difference between the number of Republican seats and the number of Democratic seats at stake in the election, and a dummy variable for the president’s party. Although it asks specifically about House voting intentions, the generic ballot question predicts Senate voting as well. The seat difference variable is a measure of party exposure in the election: the more seats a party has at risk relative to the opposing party, the more seats it tends to lose. Finally, the dummy variable for the party of the president reflects the tendency of the president’s party to lose seats in midterm elections even after controlling for the other predictors in the model.
Table 3 presents estimates for the effects of the three predictors on change in Republican Senate seats based on data for all 17 midterm Senate elections since World War II. The estimated coefficients for all three predictors are in the expected direction and highly statistically significant. Moreover, the model explains an impressive 75% of the variance in Senate seat swing. This number is substantially less than the 90% of variance in seat swing explained by the House forecasting model. However, this result is to be expected given the much smaller number of Senate seats at stake in each election and the larger proportion of competitive contests in Senate elections.
Table 3 Results of Regression Analysis of Senate Seat Swing in Midterm Elections
Note: Dependent variable is change in Republican Senate seats.
Source: Data compiled by author.
The values of two of the predictors in our model make it clear that 2014 is likely to be a difficult year for Democrats in the Senate. First, because six more Democratic than Republican seats are at stake this year, Democrats would be expected to lose 2.4 Senate seats compared with an election in which there were equal numbers of Democratic and Republican seats at stake. Second, a Democrat in the White House means that Democrats can expect to lose about four more seats than they would expect to lose in a midterm election with a Republican in the White House.
When we add together the effect of the seat exposure variable and the effect of the midterm dummy variable, and factor in the intercept of -0.9 in the regression equation, Republicans start the 2014 campaign with an expected gain of 5.7 seats. That number is very close to the six seats that Republicans need to regain control of the Senate.
The only predictor that is not yet set for 2014 is the generic ballot variable and that will not be known until early September—results from much earlier than the late summer or early fall have less value in predicting seat swing. However, because the values of other two predictors—seats at stake and the party of the president—are already set, we can make conditional predictions of seat swing in the 2014 Senate elections depending on the results of the generic ballot question in early September. Those conditional predictions are displayed in table 4.
Table 4 Conditional Forecasts of Change in Republican Senate Seats
Source: Data compiled by author.
Once again, the conditional forecasts in table 4 make clear that the fundamentals in 2014 are very favorable for Republicans in the Senate elections. Because a Democrat is in the White House and Democrats have 21 seats at stake compared with only 15 seats for Republicans, Republicans are almost guaranteed to make gains in the 2014 Senate elections. Even if Democrats have a 10-point lead on the generic ballot in early September, Republicans would still be expected to gain between three and four Senate seats because of the Republican advantage on the seat exposure and midterm party variables. On one hand, a Democratic lead of five or more points on the generic ballot would give Democrats a better than 50/50 chance of retaining control of the Senate. On the other hand, a Republican lead of five or more points would almost ensure a GOP majority in the 114th Senate.
Based on the average of generic ballot polls during the past two months, the most likely outcome of the 2014 Senate elections is a Republican gain of 5–6 seats. The good news for Democrats is that any Republican majority in the 114th Senate is almost certain to be very narrow, and the large number of Republican seats that are up for grabs in 2016 would give Democrats an excellent chance of regaining control of the Senate then.
Regardless of which party is in the majority next year, the long-term outlook for the Senate is for a continuation of narrow majorities with party control at stake every two years for the foreseeable future. This situation is likely to encourage more of the intense partisan conflict that has recently characterized the Senate. Moreover, the next Senate is almost certain to be even more ideologically polarized than the current Senate. The replacement of several moderate Democrats with very conservative Republicans will increase the already wide ideological divide between the parties. This situation may lead to further erosion of the filibuster rule and other Senate practices that allow the minority party to obstruct, delay, or defeat decisions supported by the majority party. For better or worse, the result of these trends is likely to be the transformation of the Senate into a body that much more closely resembles the House of Representatives.
