Who turns out to vote is believed to favor the GOP in midterms, but changes in the electorate may not make so much difference
Barack Obama won the 2008 presidency by 7.3pt. Two years later, his Democratic party lost 63 seats and control of the House of Representatives. Two years after that, Obama won re-election by 3.9pt. The incongruity of the middle result has led people to wonder why Democrats did better in the presidential years but did worse in the midterm election.
Did Democrats do so poorly in 2010 because of poor turnout among their core constituencies: minorities and young voters? After all, the percentage of eligible voters that turns out drops by about 20pt between midterm and presidential years. Are most of those minority and young voters? If so, Republicans would have fared far worse in 2010 with presidential year turnout and will do well in 2014.
If you look at the exit polls, the minority share of the electorate went down from 26% in 2008 to 23% in 2010. The 18- to 29-year-old percentage of the electorate fell from 18% to 12%, while the 65-year-old and older percentage of the electorate rose from 16% to 21%. But are these data correct, and what type of effect do they have?
I believe the minority share of the vote did not drop by 3pt. The Current Population Survey (CPS), which most would agree is far better at picking up changes in the electorate and matching pre-election surveys, shows a drop of only 1.2pt, from 23.7% in 2008 to 22.5% to 2010. Such a drop is not unusual and is consistent with the 1.2pt drop from 2004 to 2006, even as the Democrats romped in the 2006 midterms with an 8pt victory in the national House vote.
We can figure how much of a difference this change in the racial make-up of the electorate makes by multiplying the percentage of whites won by the Democrats by the percentage of the vote they made up of the electorate in 2008 and 2010, and doing the same for non-whites. Applying the racial turnout from the 2008 election to the 2010 election would have slimmed the Republican margin by less than 1pt from the 6.6pt victory they took in 2010. This would have been more than enough to take 50-plus seats and recapture the House.
Even if you apply the drop-off seen in the exit polls, the Republicans would have won by more than 4pt. Again, this would have been more than enough to take back control of the House.
What about the youth effect? The CPS showed a drop in the 18- to 29-year-old vote from 17.1% in 2008 to 11.3% in 2010. This 11.3% is virtually identical to the 11.2% that 18- to 29-year-olds made up in the Democratic romp of 2006. Meanwhile, the share of the 65-year-old plus vote climbed from 19.5% in 2008 to 23.9% in 2010. That may seem a lot, but keep in mind that the voting differences between age groups is far less than the differences in voting between racial groups. Non-whites voted 38pts more Republican than whites in 2010, while 18- to 29-year-olds voted only 17pt more Democratic than voters 65 years and older. So, it isn’t surprising that the total age impact of 2010 versus 2008 is about 2pt on the margin, despite the comparatively wide turnout differences between age groups.
Combining the impact of race and age, you’d be looking at a 3pt Republican gain between the 2008 and 2010 electorate. That still would have been enough for the Republicans to win more than 45 seats and win back the House. Keep in mind, though, the largest portion of the electorate that is “minority” are youth. Putting together the age and race effects, therefore, may make the presidential and midterm electorates seem more different than they are.
Perhaps the best way to check whether the electorate changes between midterms and presidential years is to look at data from Pew Research. Pew, a pre-eminent pollster that has led the way in developing sampling techniques that get full coverage of the American population, publishes registered and likely voter data just before each election. Unlike other pollsters whose likely voter electorate were a less accurate estimate of the 2012 result, Pew’s likely voter data were closer than its registered data. In fact, its likely voter data has been more accurate in every election except one since 2002. This suggests that they are picking up something very real.
We can compare the likely voter to registered voter gap in midterms and presidential elections in Pew polls to see if Republicans really do have a turnout advantage in midterm elections. The likely voter to registered voter gap in 2010 was 7pt. That is, Republicans led by 6pt in the likely voter result, while trailing by 1pt among registered voters. That may seem like a big gap, but bear in mind that the difference was 4pt in both 2008 and 2012. In the 2006 midterms, it was also only 4pt. In fact, the average difference between Pew’s likely voter and registered voter result in midterm elections over the past decade, as the Democratic-leaning millennials have joined the electorate, has been 4.3pt. The average difference in presidential years has been 4pt.
The Pew data suggest that Republicans are actually not gaining an advantage; or if there is one, it’s minimal. My own estimate is that it’s probably about 2pt when looking at all the data. That’s consistent with the idea that the current party affiliation differences between age groups has disadvantaged Democrats in midterm elections, while the differences in turnout by different racial groups likely don’t have much of an effect. This gap between midterm and presidential year electorates has developed recently, as Democrats used to be quite popular with the older voters of the “greatest generation”, though they are significantly less liked by the older voters of the “silent generation”.
Two points is certainly not nothing, yet it’s not a ton either. President Obama won by nearly 4pt in 2012. Republicans would definitely have won the House and comfortably so in 2010, even with a 2008 electorate. If Republicans win big in 2014, the difference in the electorate will only be a small part of it. But if they were to barely hold onto the House, then demographics may have made the difference.
Then again, other factors will have played a bigger difference, such as the usual “penalty” the president’s party suffers in midterm elections or a possible backlash against Obamacare.