Even though the general election is not until November, we already know that the Texas Senate will be substantially more conservative in 2015 than in the past. There will likely be eight new senators; four replacements will definitly be more conservative than the previous senators, three replacements for very conservative senators will likely be at least as conservative and the one remaining seat will turn very conservative if the Republican wins. These senator replacements will join three newely elected senators from the last election that are also very conservative.
In light of all these conservative candidate wins, I suspect the remaining Republican senators will be trying to demonstrate their own conservative credentials with an eye towards the next election.
Ross Ramsey writing in the Texas Tribune explains it all in detail in his article Voters Tilt the Senate to the Right.