Shutting down the U.S.-Mexico border would allow thousands of Customs and Border Protection officers stationed at ports of entry to instead help Border Patrol agents stationed in between those crossings, where as many as 4,000 people are being encountered daily, according to a Border Patrol union spokesman.

Chris Cabrera, a Border Patrol agent and National Border Patrol Council spokesman, on Monday said President Trump's threat to shudder operations between the U.S. and Mexico could prompt migrants to attempt to illegally enter the country, but he said CBP would be in a better position to respond.

"If they close those ports of entry, we can use those agents to help us out in the field to get a control over what's going on. It's so far out of hand you guys wouldn't believe it if you saw it," he told CNN Monday.

Cabrera's Rio Grande Valley Sector in Texas has seen more apprehensions of people illegally crossing from Mexico to the U.S. than any of the nine sectors on the southwest border.

Of the more than 66,000 migrants taken into custody in February, more than 25,000 took place in the South Texas region.

Cabrera said last week that the region made 9,000 apprehensions but warned that agents do not know how many others evaded arrest.

"That's not even counting the hundreds or thousands that are getting away from us because we don't have the manpower out there , " he said.

Shutting the southern border would interrupt $821 million of trade daily. The Trump administration threatened the move in December when immigrant apprehensions began ticking up, but he did not follow through.

Last Friday, Trump again threatened to close the border