27% of Republicans in the state say Cruz would be their top choice for the nomination to 15% for Jeb Bush, 11% for Rand Paul and Chris Christie, and 9% for Paul Ryan. Perry comes in 6th place at 7%, leading only Marco Rubio at 6%, Rick Santorum at 4%, and Bobby Jindal at 3%.
Source: http://www.publicpolicypolling.com/main/2013/07/texas-miscellany.html
Cruz is absolutely crushing (39%) the very conservative vote there, I think a lot of that would go to Rand should Cruz not run. In crosstabs that seem to defy belief, Rand is in last place amongst the 18-45 age group, tied with Bobby Jindal getting 2% of the vote.