Texas Republicans have spent years trying to crack down on illegal immigration across the southern border with Mexico. Emboldened by the election of Donald Trump, however, the time may finally be right for the GOP to mobilize an assault on loosely defined "sanctuary cities," especially with two large counties eyeing such policies. Texas Gov. Greg Abbott has pushed the issue to the front of his unofficial agenda for 2017, pledging in interviews and on social media to sign into law a "ban" on cities and local governments that are seen as protecting people in the U.S. illegally, with sanctions such...