A few Republican incumbents in the U.S. House are probably sweating right now. Keep an eye on Lance Gooden, Craig Goldman and Pete Sessions. And the 32nd Congressional District, which was the safest of the seats Republicans redrew last summer, also looks to be in danger.

Gabby Birenbaum is the Washington Correspondent for the Texas Tribune. She covers the Texas congressional delegation and the impact of federal policy on Texas. Gabby previously covered Washington for The...