The Party Line
Wed October 31, 2012
Expect Republicans To Keep Control Of General Assembly
Along with the various congressional races that could help the GOP keep control of the U.S. House, there are many state legislative races in which districts were redrawn to benefit the party in power.
One way to classify these new districts is to use the partisan voting index system developed by Charlie Cook, of the Cook Political Report in Washington, to classify U.S. House seats.
In Cook’s index, a district can be classified based on the average presidential election returns of that district for the past two cycles, in comparison to the national average that each party’s candidate received.
For example, in 2004 John Kerry received 48 percent of the national vote, but in a hypothetical district he received 58 percent of the vote — meaning that the district overperformed by 10 points. Then, in 2008, when Barack Obama got 53 percent of the national vote, the district went 65 percent — a 12-point difference.
Taking two differences and averaging them gets you a D+11 rating, meaning that a Democratic candidate would be expected to receive 11 percentage points more votes than the national average.
Taking this approach, I used the statewide performance of the presidential candidates as the comparison baseline and ran the similar numbers for the new state house and state senate districts after the redistricting efforts.
Here are the maps for the new NC House of Representatives and the NC Senate:
In classifying the districts, any district with an average of over 10 points could be considered a “likely” district for the favored party. For example, the most Democratic NC House district is number 29, with a D+37 — meaning, that the Democratic candidate should receive 37 points more than the Democratic presidential candidate’s statewide performance.
On the opposite end of the spectrum, NC House districts 78 and 73 both had a R+20 scores.
With scores above 10, we would strongly suspect that one party over the other would be strongly favored in that district.
In looking at the districts with an average below 10 points, we could break them into two categories: those with averages between 3 and 10 could be “lean” districts, while those below 3 could be considered “toss-up” districts.
While Democrats and Republicans appear to be somewhat balanced in those districts that should strongly favor (“likely”) one party over the other (GOP with 36, Democratic with 30), it is in the districts that “lean” to one party over the other that the GOP advantage in redrawing the district lines tends to favor.
If Republicans were only able to secure the “likely” and “lean” districts in their columns, they would have a cushion of 14 to secure their majority of 61 seats.
In the NC State Senate, a similar pattern emerges out of those newly drawn districts as well.
With a needed majority of 26 to control the upper chamber, Republicans appear to have created an even balance between the strongly favored districts (14 each), but like in the house maps, 17 districts appear to “lean” to the GOP while only 2 senate seats appear to lean to the Democrats.
So, if we use the average of past presidential performance in the new districts as a possible predictor, the Republicans should hold both chambers of the North Carolina General Assembly with comfortable margins.