(WASHINGTON) — Texas Gov. Greg Abbott sent a letter to Joe Biden on Wednesday urging the president to, as Abbott described it, carry out his constitutional obligations to protect the country from what Abbott called an “invasion” of migrants at the southern border.

Abbott slammed the president’s policies, contending that Biden’s “inaction has led to catastrophic consequences” for Texas communities. The governor, a major Republican critic of Biden’s, has increasingly focused on the issue of immigration, facing backlash from migrants’ advocates and the Biden administration as a result.

“You must reinstate the policies that you eliminated, or craft and implement new policies, in order to fulfill your constitutional duty to enforce federal immigration laws and protect the States against invasion,” Abbott wrote.

His letter reflects his push to ramp up his rhetoric about what he has called the Biden administration’s “open-border policies.”

On Tuesday, Abott tweeted that he had “invoked the Invasion Clauses of the U.S. & Texas Constitutions to fully authorize Texas to take unprecedented measures to defend our state against an invasion.”

In the tweet, the governor included a list of actions he said he had constitutional authority to take, including deploying gun boats to parts of the border, deploying Department of Public Safety officers to arrest immigrants who have crossed illegally into the United States and building parts of the border wall.

That announcement sparked a series of misleading headlines that Abbott had officially declared an “invasion” at the southern border, a move that would give him added authority to activate local state law enforcement agencies to deport migrants.

Abbott’s budget director, Sarah Hicks, was asked Tuesday about the tweet during her testimony before the state’s Senate Committee on Border Security and she reassured the panel of Texas legislators that the governor was not announcing a new strategy, but was rather reiterating some of the actions he has already taken to stem illegal immigration.

“I don’t think it is a change in overall tactic as much as it is a reminder to all of us, to Congress and to the members working the issue that this is serious and it demands a full and serious response,” Hicks said.

Since Biden took office last year, Abbott has issued a series of executive orders aimed at curtailing immigration. In July, he authorized state law enforcement to return migrants suspected of entering the country illegally to ports of entry. That move has been criticized by immigration advocates and rights organizations who say it endangers migrants and may leave people who are lawfully hoping to claim asylum susceptible to racial profiling.

On Wednesday, the governor sent another letter to the Texas Department of Public Safety and the Texas Military Department urging them to “expand their unprecedented efforts to combat the growing illegal immigration along the Texas-Mexico border.”

“You have an essential assignment: Use every available tool and strategy to fight back against the unprecedented invasion that Texas is seeing at our border. Until Congress acts or the Biden Administration does its constitutionally required job, Texas Guardsmen and Troopers must bear the burden of securing the border. You must continue to keep Texans and Americans safe and protect against an invasion of the southern border. I order you to use all resources and tools available to repel immigrants from attempting to cross illegally, arrest those who cross illegally and return them to the border, and arrest criminals who violate Texas law,” the governor wrote.

Aaron Reichlin-Melnick, policy director at the American Immigration Council, told ABC News that Abbott may be overstepping his authority by saying he can declare an invasion at the border.

“The reality is that no governor can unilaterally declare that they’re being invaded by migrants to take over basic immigration enforcement practices. The U.S. Constitution does not authorize governors to usurp federal immigration authority and no matter how you look at it, migrants seeking asylum are not invading,” he said.

Abbott’s office did not respond to a request for comment; neither did the White House.

Reichlin-Melnick said he believes Abbott’s use of the word “invasion” is especially dangerous because Texas is home to one of the deadliest attacks on Latinos: the 2019 mass shooting at an El Paso Walmart that killed 23 people. Investigators have said the El Paso gunman wrote a screed posted online saying the massacre was in response to an “invasion” of Hispanics coming across the southern border.

“I think we have seen the dangers of harsh rhetoric against migrants,” Reichlin-Melnick said. “The El Paso shooting is the best example of that. It occurred in his own state and it involved a person who believes that the state is being invaded by Latinos, killing dozens of people. Rhetoric about invasions inflames the issue, it doesn’t promote compromise.”

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