The Department of Homeland Security (DHS) is preparing to ask the Pentagon to extend the deployment of thousands of troops near the southwestern border and to send additional troops to erect barbed wire and barriers, CBS News has learned.

The request would extend the military's operation at the border, which is set to end on Jan. 31, and deploy additional engineers to erect 160 more miles of concertina wire. So far, the military has erected 70 miles of fencing.

In late October, the Trump administration deployed more than 5,000 active-duty soldiers near the U.S.-Mexico border to assist the Border Patrol and National Guard units already stationed there. The White House and DHS said the operation was designed to anticipate the arrival of caravans of migrants from Central America, but critics denounced it as a politically motivated maneuver to galvanize President Trump's base ahead of the November midterm elections.

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Mr. Trump's rigid stance on border wall funding and Democrats' refusal to budge to his demands have fueled an impasse in budget negotiations on Capitol Hill. The government has been partially closed since Dec. 22 and the shutdown has stretched into the new congressional session, when Democrats took control of the House.

Former Secretary of Defense James Mattis left the administration at the end of the year after Mr. Trump dismissed him prior to his planned departure date in February. Deputy Defense Secretary Patrick Shanahan is serving as acting secretary as the administration searches for a permanent replacement to lead the Pentagon.