The Defense Department’s inspector general’s office will audit a $400 million border wall contract that the U.S. Army Corps of Engineers awarded to a North Dakota construction company run by a GOP donor whom President Trump repeatedly urged military officials to hire.

Glenn A. Fine, the top official at the Pentagon office, authorized a review of the contract in response to a Dec. 4 letter from Rep. Bennie Thompson (D-Miss.), chairman of the Homeland Security Committee, asking inspectors to take a closer look. Fine informed Thompson of the audit in a letter Thursday.

“You raised concerns about the possibility of inappropriate influence on USACE’s contracting decision, and questioned whether the bid submitted by Fisher Sand and Gravel Co. met solicitation standards,” Fine wrote in his letter to Thompson. “You also questioned whether USACE made the award in accordance with federal procurement law and regulations.

“In response to your request, we have decided to initiate an audit of the solicitation and award of this contract. We are assessing the methodology of that audit and will formally announce the audit soon.”

On Dec. 2, the Pentagon announced a contract worth up to $400 million to Fisher Sand and Gravel for the construction of 31 miles of new border barriers along the Cabeza Prieta National Wildlife Refuge in southern Arizona.

After its previous bids on projects for the border barrier were passed by the Army Corps, Tommy Fisher, the company’s chief executive, launched an aggressive public and private campaign to win a contract. He made several appearances on Fox News promoting the superiority of his company, while Sen. Kevin Cramer (R-N.D.) personally lobbied the president to hire Fisher while accusing the Army Corps of unfairly excluding the firm. Fisher donated to Cramer’s Senate campaign, appeared with Cramer on the campaign trail and was Cramer’s guest at Trump’s State of the Union address earlier this year.

Fisher has paid lobbying firm Odney more than $100,000 since 2017 during its push to secure border wall contacts, disclosure records show. The company also has partnered with right-wing activist group We Build the Wall to construct fencing on private land with millions of dollars raised through online donations.

The group is led by several prominent GOP figures: ex-Trump adviser Stephen K. Bannon is chairman of the group’s advisory board, and its general counsel is immigration hard-liner Kris Kobach, Kansas’s former secretary of state. Blackwater USA founder Erik Prince is also a board member, along with former Major League Baseball pitcher Curt Schilling.

We Build the Wall is attempting to install a 3.5-mile span of privately funded fencing along the banks of the Rio Grande near Mission, Tex., on land the group says Tommy Fisher purchased.

A federal judge has issued a temporary restraining order that blocks the group from putting up the barrier because the group is planning to build along the river’s flood plain and would need a permit from the International Boundary and Water Commission to continue.

The U.S. government joined other plaintiffs in suing the group to stop Fisher’s bulldozers. During court hearings, Kobach said We Build the Wall has provided just 5 percent of the funding for the project, and the judge agreed to remove the group from the lawsuit, leaving Fisher as the defendant.

Tim Priebe, an attorney who represents Fisher, told the court that the company wants to help the government acquire private land it needs for Trump’s barrier project. Priebe told the court that Fisher is prepared to spend “a ton of private money”on the effort, according to the Progress Times in Mission.

Alice Crites contributed to this report.