abbot immigration
Texas Gov. Greg Abbott spoke at a joint press conference Feb. 18, 2015, in Austin, Texas, about a lawsuit filed by a Texas-led coalition of 26 states challenging President Obama's executive action on immigration. Erich Schlegel/Getty Images

The governor of Texas had a stern warning Monday for the top law enforcement official in Dallas County: Enforce the nation's laws, or else. Gov. Greg Abbott, a Republican, addressed Sheriff Lupe Valdez in a letter, regarding her using her own discretion -- rather than following federal law -- in cases involving detention of undocumented immigrants jailed on minor crimes.

“Your refusal to fully participate in a federal law enforcement program intended to keep dangerous criminals off the streets leaves the state no choice but to take whatever actions are necessary to protect our fellow Texans,” Abbott wrote, as reported by the Texas Tribune. “Policies like yours compel Texas to take action to protect Texans’ safety.”

In particular, Valdez has been refusing to adhere to a federal law mandating all undocumented immigrants in jail be held at least 48 extra hours after their release dates to afford the U.S. Immigration and Custom Enforcement ample time to investigate the circumstances surrounding the jailings. For her part, Valdez, a Democrat who is in the throes of a re-election campaign, has said her decisions are made on a case-by-case basis and are what's best for her jurisdiction. Dallas County has a population that is 39.3 percent Hispanic or Latino, according to the most recent Census estimates.

“No matter what we do, someone is going to get upset,” she told the Dallas Morning News earlier this month. “We can’t base our decisions on who is going to get upset with us. We have to base our decisions on what is best for the whole.” It was immediately unclear if she had responded to Abbot's letter Monday.

The concept of sanctuary cities -- or cities that extend certain legal liberties to undocumented immigrants -- has come under scrutiny lately as immigration becomes an increasingly contentious topic during the national and local election season. The Republican Party has been pressuring Abbott to encourage legislative members of his party to draft a bill to rid the state of so-called sanctuary laws that do not encourage deporting undocumented immigrants, according to the Texas Tribune.

Unauthorized Immigrant Population by State | InsideGov

Conservative advocates in Texas have been arguing for Abbott to take action, but so far Monday's letter is apparently the most he's done.

"This is a simple matter of public safety and national security," said JoAnn Fleming, director of Grassroots America We The People, a nonprofit organization pushing for the end to sanctuary policies.