Gov. Greg Abbott on Thursday cleared state authorities to return migrants they apprehend to the border, setting up a potential clash with the federal government over the authority to enforce immigration law.

Immigration law enforcement is a federal responsibility. Abbott appears to be testing the limits of state authority by empowering state law enforcement and National Guard troops under state deployment to bring migrants to the ports of entry — stopping short of using state resources to expel migrants from the country, as immigration hawks have increasingly called for in recent months.

It was not immediately clear how state law enforcement would determine which migrants should be transported.

Despite the state’s allocation of $4 billion for border security and the deployment of thousands of National Guard troops and state police to the border, Abbott has faced growing pressure from within his party to assert a stronger state role and invoke “invasion” powers under the U.S. Constitution. Such a declaration, some Texas Republicans contend, would give states solid legal ground to invoke war powers to allow the state’s National Guard to deport migrants. The idea has been widely derided by legal experts as a political ploy, and Abbott earlier this year expressed concern that it could expose state law enforcement to federal prosecution.

But on Thursday, Abbott stopped just shy of fulfilling those requests.

The executive orderallows the Texas National Guard and Texas Department of Public Safety to apprehend “immigrants who cross the border between ports of entry or commit other violations of federal law, and to return” them to ports of entry. It is unclear from the executive order what state authorities would do with the migrants once they returned them to the ports of entry, which are manned by federal immigration authorities.

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