Given a list of possible threats to the country, 22 percent chose illegal immigration, followed by 18 percent who chose foreign terrorist groups such as ISIS and Al Qaeda. Other issues trailed behind, including political polarization, decaying infrastructure, gun violence and unfriendly foreign nations.

"Even before the terrorist attacks in Paris last Friday, Texans expressed deep concern over border security," said Daron Shaw, co-director of the poll and a professor of government at the University of Texas at Austin. "I may be going out on a limb here, but I doubt Texas voters agree with Bernie Sanders' statement [in Saturday's Democratic debate] that climate change represents a more urgent threat than jihadist terrorism."