Despite the greater diversity of the Texas legislature in recent years, one of the factors that has maintained continuity with traditional patterns in the make-up of the membership is the advantage of incumbency. Historically, there has been very slow turnover of the membership: a pattern that continues today. The 2007 - 2008 Senate, for instance, had only five members, or about 6.2 percent, who were new. In that same legislature, the House, with its shorter terms of office, had twenty-three new members, or 15 percent.
In the aftermath of the volatile 2010 elections, the Senate had no new members; the House, however, had 38 new members. Twenty-two of those new members defeated sitting incumbents. The defeat of several members who served only one term and represented competitive districts suggest that these members may not have been able to take full advantage of their status as incumbents. They were not well established in districts with closely matched numbers of Republican and Democratic voters.
After the 2012 elections, the Senate has five new members, only one of which defeated a sitting incumbent; the House has 41 new members. While only 12 of these new members defeated sitting incumbents, 9 of those defeats came in the Republican primary, an indication of the increasing competitiveness within the state's dominant party. The high turnover also reflected a number of retirements.
Incumbency is a huge advantage when running for legislative office because it allows more opportunities for name recognition. A voter merely recognizing a candidate's name can provide a critical advantage because of the large number of offices for which Texans vote. As voters move down the ballot (to "down-ballot" contests like those for state legislator), they have to rely on less and less knowledge of the candidates. Often voters will vote for a candidate in these races simply because they recognize - or think they recognize - the candidate's name.
Incumbency also helps candidates raise campaign money from powerful special interests. If you've supported a special interest's position on legislation, campaign contributions are a common way of recognizing support. But only incumbents have this opportunity. As a general rule, special interests will bet more money on an incumbent than a challenger, even where special interests see challengers as potentially supportive, because of the expectation that the incumbent will win. The primary goal for special interests is to be on the winning side in any election. As a result they are likely to play the odds and bet on the candidate most likely to win, the incumbent. All things being equal, incumbency and the support of contributors are thus mutually reinforcing.
The state's much more competitive political environment, combined with redistricting, generated a relatively high turnover rate in the 78th Legislature. These factors contributed to the ability of the Republican Party to finally gain its long sought after majority in both the House of Representatives and the Senate. The 2010 mid-term elections led to another legislative session with a large number of incumbents defeated, all but one of whom were Democratic incumbents defeated by Republican challengers.
Despite its importance in determining the membership of the Texas legislature, incumbency is less of a factor there than it is in the United States Congress, as comparison of historical incumbency success rates in the two bodies illustrates.