EXCLUSIVE: The Biden administration spends about $130,000 per day to store and maintain unused border wall panels at the southern border, and Senate Republicans are demanding answers.

Republican members of the Senate Armed Forces Committee — using details provided to them in a request for information to the U.S. Army Corps of Engineers (USACE) — sent a letter Wednesday evening to the Defense Department asking why nearly $50 million is being spent each year to store the Trump-era border materials.

Led by ranking member Sen. Roger Wicker, R-Miss., and signed by Texas Sens. Ted Cruz and John Cornyn, along with nearly every other Republican on the committee, the senators wrote that they "are disturbed to learn the Department of Defense is paying private landowners to store border wall materials procured under the Trump Administration instead of fortifying the southern border with those materials."

"At present, over 20,000 border wall sections, otherwise known as bollard panels, lie unused at 20 project sites across southern Arizona and New Mexico," the senators said in the letter addressed to Melissa Dalton, the assistant secretary of defense for homeland defense and hemispheric affairs. "Every day, the Department of Defense pays $130,000 to store, maintain, and secure these materials. Since you were sworn in as the Assistant Secretary of Defense for Homeland Defense and Hemispheric Affairs a year ago, you have allowed the Department to pay over $47 million to store these panels. The Department of Defense should not be incurring these daily charges but should be using these funds to bolster national security."

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"This failing program clearly misses that standard," the senators added.

In its correspondence with the committee, the USACE confirmed the cancelation of the border wall contracts by President Biden's administration in 2021 "left a variety of excess materials" and the "total costs to store, maintain, and secure all the materials across all sites is estimated to be approximately $130,000 per day."

"Some of these materials, to include security cameras, overhead lights, and electrical and stormwater materials are being disposed of in accordance with federal excess material disposal laws and regulations," the USACE stated. "Overall, 61% of non-bollard panel materials, and 4% of bollard panel materials have been transferred to other government agencies or disposed of through the DLA disposition process. The total value of these materials is estimated at approximately $300 million. However, the cost to the government cannot be finalized until audits are completed and negotiations with contractors are concluded."

unused border wall materials

A pile of steel bollards used to build the U.S.-Mexico border wall are seen abandoned at Guadalupe Canyon, east Douglas, Arizona on September 20, 2022. (GUILLERMO ARIAS/AFP via Getty Images)

The senators also pressed Dalton on why the remaining unused bollard panel materials are not being disposed of by the Defense Department, a required government process for the department that works in coordination with the Defense Logistics Agency (DLA) to reutilize, resale, or demilitarize military property.

"We assume you are well aware of this capability since the Department used the program to transfer 1,700 border wall panels to the state of Texas early in your tenure," the senators wrote. "It has come to our attention that only 4% of the excess bollard panel materials have been transferred. We urge you to pursue all possible avenues to sponsor or endorse the reuse of excess Department of Defense property, including further transfer to states."

Attached to the letter to Dalton was a series of questions from the committee regarding "internal correspondence" that led to the storage of materials at high costs rather than being disposed of, as well as a list of the entities and individuals who are being paid by the DOD to store the border wall panels on private land and how those agreements were arranged.

unused border wall materials

Piles of unused border fence sit at one of the border wall construction staging areas on the Johnson Ranch near Columbus, N.M., on April 12, 2021. (Bill Clark/CQ-Roll Call, Inc via Getty Images)

"I can tell you that as with all her official correspondence, ASD Dalton’s reply will be sent to the authors of the letter – and we will not have anything additional to share on that," a Defense Department spokesperson told Fox News Digital when asked about the letter.

FOX FLIGHT TEAM FOOTAGE CAPTURES MORE THAN $100M IN UNUSED BORDER WALL MATERIALS

Mississippi Republican Sen. Roger Wicker, the ranking member of the committee, told Fox News Digital the spending to store the unused materials is "holding back" efforts from lawmakers to protect Americans and secure the border.

"It is astounding to me that the Department of Defense is paying $130,000 per day to do nothing with $300 million worth of border wall materials," Wicker said. "This clear example of government waste is holding back our mission to protect American citizens and American security. President Biden appears to prefer spending money to avoid building the wall, rather than protect Americans from cartels."

The Republicans from the committee who signed the measure include: Sens. Deb Fischer, R-Neb., Tom Cotton, R-Ark., Mike Rounds, R-S.D., Joni Ernst, R-Iowa, Dan Sullivan, R-Alaska, Kevin Cramer, R-N.D., Rick Scott, R-Fla., Tommy Tuberville, R-Ala., Ted Budd, R-N.C., Markwayne Mullin, R-Okla., and Eric Schmitt, R-Mo.

The disposal of all unused border security materials, as required in the government's process to close contracts, has delayed the closure of multiple border construction contracts, according to the USACE.

The process to cancel all contracts "is still on-going and is projected to continue at a minimum through 2024," the USACE told the committee. Non-bollard materials are "scheduled to be turned in to DLA facilities by the end of March 2023" and USACE is in "discussions with DLA regarding the over 20,000 excess bollard panels," the agency added.

Sen. Roger Wicker of Mississippi

Senate Armed Forces Committee ranking member Roger Wicker, R-Miss., told Fox News Digital the $130,000 a day spending to store the unused materials is "holding back" efforts from lawmakers to protect Americans and secure the border. (Anna Moneymaker/Getty Images)

"Given the size, weight and transportation requirements for this material, significant planning and coordination may be required. Contract terminations cannot be completed until all materials have been properly disposed," the USACE told the committee.

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In October 2021, the Fox Flight Team captured footage of roughly 10,000 steel panels that have been sitting outdoors, unused, since Biden took office earlier that year. Valued at $100 million, Fox News’ Bill Melugin reported at the time there was enough steel for over 100 miles of border wall, but only about 14 miles were built before construction was halted after the Trump administration left office.

There were over 1.7 million encounters of migrants at the border in FY 21 and more than 2.3 million in FY 22. So far in FY 2023, which began in October, there have been more than a million encounters.

Fox News' Amy Nelson and Adam Shaw contributed to this article.