Today we begin our exploration of districts that may be in play in the general election by examining a metric we call “relative performance factors,” which measure the partisan lean of a district relative to the state.

Two dozen Texas congressional and legislative seats are held by Republicans in districts that are bluer than the state as a whole. Many of these districts are still friendly to Republicans, but they have been trending bluer for several election cycles. In fact, all but one of these two dozen seats has been getting consistently bluer in recent election cycles. The exception is HD43, currently held by Rep. J.M. Lozano (R-Kingsville), which is steadily getting redder.

The chart below shows the 23 Republican-held districts where Democratic statewide candidates fared better than in the state as a whole in 2016, and for which Democratic voting strength has been growing. Nine of these districts are entirely within Dallas Co., and another six are entirely within Harris Co. Clearly these two counties will be significant battlegrounds.

The average statewide Democratic candidate in 2016 received 42.5% of the vote head-to-head against the Republican candidate.** The numbers in the chart indicate how much better than 42.5% those Democratic candidates averaged in each district. For example, Democratic statewide candidates in CD23 fared 6.9% better than in the state as a whole, which means that the average statewide Democratic candidate received 49.4% of the vote there, measured head-to-head against the Republican candidates.

The bluest Republican-won district in 2016 was HD105 in Dallas Co., which re-elected Rep. Rodney Anderson (R-Grand Prairie) by 64 votes. Statewide Democratic candidates ran 8.8% better than in the state as a whole, measured head-to-head against Republican candidates. Democratic candidates for President, Railroad Commissioner, one Supreme Court seat and all three Court of Criminal Appeals seats carried the district. Collectively, the Democratic congressional candidates narrowly won the district over their Republican rivals.

HD105 was the only Republican-won district where the average Democratic statewide candidate received over 50% of the vote head-to-head against the Republican candidates. Republican statewide candidates, on average, carried each of the remaining 22 districts shown, although there were some defections near the top of this chart.

Despite occasionally wild swings in statewide Democratic candidates’ performances, the relative performance of those candidates in each district tends to remain fairly consistent. For example, Democratic statewide candidates fared 1.3% worse than their statewide average in HD115 in 2008. Those candidates averaged 44.3% statewide and 43.0% in HD115. Two years later, the average performance of Democratic statewide candidates fell to 36.5%, yet their performance in HD115 was still just 1.8% worse than in the state as a whole. Despite a statewide performance drop of nearly 8 percentage points, their relative performance in HD115 fell just half a percentage point.

In this way, we can model election outcomes based on various estimates of the overall performance of the Democratic statewide candidates. If the 2016 results carried over into 2018, and the Democratic statewide candidates received, theoretically, 46.5% against the Republican candidates head-to-head, then statewide Democratic candidates would be averaging at least 50% in the first 10 districts listed in the chart above.

The chart below shows how much the district’s political leanings have shifted, relative to the state, since 2002. The upper bars show the total shift in presidential elections from 2004 through 2016. The lower bars show the total shift in gubernatorial elections from 2002 through 2014. The shift has been greater for gubernatorial elections in 17 of these 24 districts.

Note that the districts are sorted in a different order than in the first chart. In this chart, districts are listed in descending order based on the shift in gubernatorial elections. The previous chart was sorted based on how relatively blue a district was in 2016.

To obtain these figures, we projected the current district boundaries backward in time so that the same geography is used to calculate relative Democratic performance in each election year.

The biggest shift has occurred in HD136, a Williamson Co. district currently represented by Rep. Tony Dale (R-Cedar Park). Relative to the state, HD136 voters’ have become more Democratic by 14.4 percentage points since 2002. In that year, Democratic statewide candidates fared 9.7% worse in what is now HD136 than in the state as a whole. Four years later, they fared 2.3% worse, then 0.2% better in 2010. Two years ago, Democratic statewide candidates fared 4.7% better than across the state as a whole, producing an overall shift of 14.4 percentage points relative to the state.

Read together, these two charts provide a sense of how the district’s voters have evolved over the past eight election cycles. Past performance is not a guarantee of future results, but very few districts have shown significant changes in direction since 2002. If a district turned bluer in 2016, relative to 2012, then it is a good bet that it will turn bluer in 2018 relative to 2014.

Five districts are among the top 10 listed in each chart:

  • HD115 (Rinaldi) – tied for 4th in relative performance in 2016, 2nd in overall shift from 2002 to 2014
  • HD102 (Koop) – 3rd in relative performance, 4th in overall shift
  • HD136 (Dale) – 8th in relative performance, 1st in overall shift
  • HD113 (Boos as nominee) – tied for 4th in relative performance, 10th in overall shift; and
  • HD134 (S. Davis) – 6th in relative performance, 8th in overall shift.

HD105 (R. Anderson) ranks 1st in relative performance but is tied for 14th in overall shift from 2002 to 2014. It is, however, ranked 4th in shift from 2004 to 2016.

There are no Democrat-held districts that are redder than the state as a whole. The closest is HD107, held by Rep. Victoria Neave (D-Dallas), who wrested it from former Rep. Kenneth Sheets (R-Mesquite) in 2016. That district was 8.1% bluer than the state as a whole in 2016. Next up is HD117, won by Rep. Philip Cortez (D-San Antonio) in 2016 when the district was 10.2% bluer than the state as a whole. This district has flipped in each of the last four election cycles, going to Republicans in 2010 and 2014 only to be reclaimed by Democrats in 2012 and 2016.

In the coming weeks, we will explore alternative ways of taking a district’s political temperature and, eventually, dive deep into individual districts. One of those metrics is straight-party voting trends. It’s worth noting here that Democratic straight-party voters outnumbered Republicans in HD102, HD113 and HD115 – three districts in that list of five – in 2016.

** For purposes of this analysis, we are excluding votes cast for Libertarian, Green, independent and write-in candidates. Their presence in races is not consistent from race-to-race and year-to-year, so we are focusing on the one-on-one matchups between the state’s two historically dominant parties.