The Trump administration is expected to send 800 or more troops to the U.S.-Mexico border to support border enforcement already stationed there at a time the president has called a “national emergency.”

According to multiple reports, Defense Secretary James Mattis could sign an order to that effect as early as Thursday. The troops — who are expected to be in place by next week — would be directed to help border authorities stop a caravan of thousands of Central American migrants who are making their way through Mexico toward the United States, according to CNN.

With the midterm elections approaching, Republicans across the country have been raising alarm about the threat posed by those migrants. At a rally in Houston on Monday, Trump suggested the migrants may be funded by Democrats, and claimed that some of the migrants are Middle Eastern. There is no evidence for either claim.

And earlier this week, U.S. Sen. Ted Cruz, R-Texas, said it may be necessary to staff up the border.

“I think this caravan is a serious threat,” Cruz told reporters in Houston on Monday. “When you see thousands of people pledging to come violate U.S. law, to cross into this country illegally, we have to treat that seriously.”

“We have to stop it,” Cruz added, “whether that means putting Border Patrol at the border to stop them or whether that means calling up the National Guard.”

The delegation is expected to include some active-duty forces, primarily from the Army, according to the Washington Post. CNN reported that the troops would not engage in “lethal operations” to stop the migrants, but would reinforce fencing at spots where migrants might cross, and also provide tents and medical care for border authorities. It was not immediately clear Thursday morning where along the border the reinforcements would be stationed.

The president also directed troops to the border in April in an effort to deter illegal immigration. The tide of border crossings has persisted under Trump, and the number of families crossing surged in September to record levels.

Former Texas Gov. Rick Perry deployed National Guard troops to the border in summer 2014, and Gov. Greg Abbott kept them in place after taking office.

Gov. Greg Abbott’s office did not immediately return a request for comment.

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