(CNN) The appointments of Chad Wolf and Ken Cuccinelli to the top two leadership roles at the Department of Homeland Security are invalid, the Government Accountability Office found in a new report, delivering a major rebuke to the Trump administration, which has repeatedly tried to skirt the confirmation process.
The Trump administration has increasingly relied on filling top posts with people on a temporary basis, fielding criticism from lawmakers. Senate Minority Leader Chuck Schumer immediately responded to the GAO's report Friday, saying President Donald Trump's "efforts to install political sycophants to implement his extreme policies in an end run around the law and Senate have finally caught up with him."
A Justice Department attorney said at a Friday court hearing that the Office of Legal Counsel will review the GAO's opinion and come to a decision on it.
The Department of Homeland Security -- the third-largest federal department -- hasn't had a Senate-confirmed secretary since Kirstjen Nielsen, who resigned in April 2019.
Since 2017, the department has had five secretaries -- only two of which were confirmed by the Senate: John Kelly and Nielsen. The others have occupied the role in an acting capacity, often leaving the department's leaders at the whims of the President and as a result, vulnerable to increased politicization.
Of 27 top roles at DHS, 10 are filled in an acting capacity. The three main immigration agencies under the department -- Immigration and Customs Enforcement, Customs and Border Protection and US Citizenship and Immigration Services -- have been helmed by acting officials for more than a year.
The appointments of Wolf and Cuccinelli, in particular, have previously come into question. Earlier this year, a federal judge ruled that it was unlawful to appoint Cuccinelli, an immigration hardliner chosen by Trump, to lead the agency responsible for processing US immigration requests.
The Federal Vacancies Reform Act dictates how most federal vacancies are filled. Despite the findings by the GAO, however, the administration is not legally bound to act on it. That's up to the courts, which already have pending cases challenging the appointments of Wolf and Cuccinelli.
Shortly after its release, the GAO report already came up in a court hearing over challenges against asylum rules released under Wolf. The lawsuit also calls into question Wolf's authority.
"In reading the GAO opinion, it's not binding but it was tracking quite closely what I was thinking about this issue, as stunning as it is that we're at day 500 and we still don't have a secretary installed that's nominated by the president and confirmed by the Senate," said Judge Paula Xinis of the Maryland District Court.
Justice Department attorney Jane Andersen underscored that the GAO is not binding on the executive branch.
DHS did not immediately respond to a request for comment.
The GAO found in Friday's report that following Nielsen's resignation "the official who assumed the title of Acting Secretary had not been designated in the order of succession to serve upon the Secretary's resignation." Kevin McAleenan, who previously served as Customs and Border Protection Commissioner, had succeeded Nielsen in an acting capacity until leaving the post last fall.
Wolf, who had previously served as undersecretary for the Office of Strategy, Policy, and Plans at DHS, assumed the acting secretary role with Cuccinelli as his number two.
"Because the incorrect official assumed the title of Acting Secretary at that time, subsequent amendments to the order of succession made by that official were invalid and officials who assumed their positions under such amendments, including Chad Wolf and Kenneth Cuccinelli, were named by reference to an invalid order of succession," the report concluded, noting that the legality of actions taken by the officials were referred to the DHS inspector general.
The GAO also referred the question over who should be serving as the acting secretary and the senior official performing the duties of deputy secretary to the DHS inspector general.
The department's leadership in acting positions has repeatedly found itself pursuing Trump's agenda. In the last three years, DHS has rolled out some of the most stringent immigration policies, and most recently, deployed personnel to respond to protests, some of them violent, after George Floyd's death -- nearly all under leadership that hasn't been confirmed by the Senate.
Friday's report was prompted by Democratic House committee chairs Bennie Thompson and Carolyn Maloney, both of whom have repeatedly criticized lack of permanent leadership at DHS.
Following the release of GAO's findings, the lawmakers called the report "damning."
"In light of this decision, Mr. Wolf should immediately step down and return to his Senate-confirmed position as Under Secretary for Strategy, Policy, and Plans. The President should appoint an a political career official to run the Department temporarily and follow the Constitution by swiftly nominating a permanent Secretary," the chairs wrote.
"As for Mr. Cuccinelli, a political pundit plucked by the President to serve in multiple senior roles at DHS for which he is woefully unqualified, he should immediately resign from the Federal government and retire his unprofessional official Twitter account."
This story has been updated with response from Sen. Schumer.