


Republican Senate Majority On The Way?

A Commentary By Harry Enten

Friday, May 06, 2011

If the recent budget debate has taught Americans anything, it is that the power of the gavel in Congress can be as powerful as the executive pen in the White House. In the blossoming 2012 campaign, we should, therefore, focus not only on the presidential election, but also the elections for Congress. Most analysts, myself included, believe that the Democrats face an uphill battle to re-capture the House. The main question is whether Republicans can pick up the necessary four (or three, if the Republicans win the presidency) seats to take control of the Senate. A model I have created suggests the GOP will not only gain the majority, but in fact control 54 seats in the next Senate.

Like predictions for the House of Representatives, forecasts for the Senate can be done one of two ways.

1. A seat-by-seat analysis. This method is most accurate in the closing days of an election, when polling data have been shown to be very accurate.

2. An aggregate forecast based on national variables. This method is less accurate, but can be employed without knowing certain characteristics about individual races. The model I present here is a national swing model developed with data from every presidential year Senate election since 1952.

The model predicts the percentage of seats up for reelection that the president's party will win in the Senate. To do so, it utilizes five variables:

1. The percentage of seats up for reelection controlled by the president's party. Senate elections, unlike those in the House, are held a third at a time. In 2010, Democrats only had to defend 19 of 37 (51%) seats and were able to maintain control of the Senate by winning 13 (35%). In 2012, Democrats control 23 (or 70%) of the seats up, while Republicans only need to defend 10 (30%). Even if the Democrats were able to win 58% (well more than half) of the Senate elections in 2012, they would still lose four seats and control of the Senate.

2. The number of military fatalities per million of the general population over the last four years in unprovoked foreign conflicts started by the president's party or maintained for more than four years under the current president's party. If President Obama had started a war with fatalities, we would expect his party to lose seats in the Senate. He has not started or continued for more than four years any war. This variable has no value for 2012.

3. Weighted quarter-on-quarter growth in real disposable income per capita (a variable originally described by Douglas Hibbs) over the current president's term. Obama's current projected real DPI growth (using Bureau of Economic Analysis data for past quarters and Wells Fargo's forecast for the future) would rank 11th of 16 presidents since 1952. Not surprisingly, this slow growth does not bode well for the president's party in the Senate.

4. An interaction variable between quarter-on-quarter real DPI growth and a simple dummy variable for whether the president's party is in control of both houses of Congress. The president's party does better when Congress is controlled by his party and quarter-on-quarter real DPI growth is positive, but does worse when growth is negative. Since Republicans control the House, this variable takes no value for 2012.

5. A Congress dummy variable for whether the president's party is in control of both houses of Congress. This variable is only included for the model to be statistically correct (due to the interaction term), but it is not statistically significant to any great effect. It has no value for 2012.


But should the model's results be believed?




At this point, this much is certain:

1. The Democrats are in great danger of losing their Senate majority in 2012. History is against them maintaining control of the Senate.

2. We will get a better gauge of the exact Senate picture when we know the candidates running in each race.

3. The true test of this Senate model's predictive value will come in November 2012.

This column was courtesy of Sabato's Crystal Ball.

Harry Enten, a senior at Dartmouth College, is pursuing a degree in government with a concentration in statistics and elections. He has previously interned at the NBC Political Unit in Washington D.C. and Pollster.com. He blogs at Margin of Error and tweets @ForecasterEnten.

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