The Department of Homeland Security on Monday fired back at what it called a “baffling” report by the Government Accountability Office that acting Secretary Chad Wolf's and acting deputy Ken Cuccinelli's appointments were invalid.

“The GAO’s conclusions are baseless and baffling,” Chad Mizelle, the senior official performing the duties of the general counsel, said in a letter, obtained by Fox News, in response to the report by the GAO issued Friday.

SCHUMER CALLS FOR DHS CHIEF TO RESIGN AFTER GAO CONCLUDES APPOINTMENT WAS INVALID

The GAO said in its report that the appointments of Wolf and Cuccinelli were made invalidly due to errors made by officials about the line of succession for filling posts in an acting capacity. Specifically, it said that when former DHS Secretary Kirstjen Nielsen resigned in April 2019, the order of succession dictated that the director of the Cybersecurity and Infrastructure Security Agency should take over. Instead, Kevin McAleenan, who was the head of Customs and Border Protection, was appointed as her successor.

DHS mistakenly referred to regulations that spelled out the process for a disaster or catastrophic emergency, rather than the typical order of succession, according to the GAO.

“Mr. McAleenan would have been the appropriate official had Secretary Nielsen been unavailable to act during a disaster or catastrophic emergency, the report said. "That was not the case here.”

McAleenan subsequently revised the succession process -- allowing Wolf and Cuccinelli to be appointed to their posts. But, the GAO found, because McAleenan was invalidly appointed, so were the changes he made to the order of succession.

“As such, Mr. McAleenan did not have the authority to amend the Secretary’s existing designation," the report said. "Accordingly, Messrs. Wolf and Cuccinelli were named to their respective positions of acting secretary and senior official performing the duties of deputy secretary by reference to an invalid order of succession."

GAO FINDS ACTING DHS CHIEF WOLF, DEPUTY CUCCINELLI INVALIDLY APPOINTED TO POSTS

The opinion is not legally binding, but it could be used as a way to challenge the decisions made during the tenures of Wolf and Cuccinelli. Senate Minority Leader Chuck Schumer responded to the report by calling for both officials. GAO said it was not reviewing the legality of the actions taken by the officials and is instead referring it to the department's inspector general.

But DHS responded Monday by calling for the report to be rescinded and describing its conclusion as “fundamentally erroneous,” before accusing the office of having neglected evidence and subsequent designations.

“The report is premised on multiple errors. Most prominently, it rests on the faulty contention that when then-Secretary Nielsen stated that then-Commissioner McAleenan would be her successor and swore him in as her successor, those actions had no legal significance in determining whom she actually chose as her successor,” Mizelle wrote. “That error doomed the report.”

It goes on to argue that the 2002 Homeland Security Act gives exclusive authority to the secretary to determine the order of succession. It argues that she made an unambiguous designation of McAleenan as her successor, and his swearing-in supplanted any other designation.

“It follows, then, that Acting Secretary Wolf and ... Cuccinelli are lawfully performing their current roles at DHS,” Mizelle argues.

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The letter goes on to further criticize the GAO’s reasoning and to raise question’s about the watchdog’s motivations for not only its conclusions but the timing of the report itself -- as well as noting that the GAO has repeatedly come under fire for partisan behavior.

“Does the timing of the report suggest that something else is motivating this opinion? Does the GAO’s unfortunate history of issuing partisan and inaccurate reports perhaps explain what is going on?” the letter asks. “As the reader reaches the report’s conclusion, he is left with the sinking and inescapable feeling that something is afoot in the swamp”