Over 400 former Justice Department employees have come out in protest of President Donald Trump’s appointment of Matthew Whitaker as acting Attorney General, demanding in a signed letter that the top official be replaced.

The ex-DOJ officials and attorneys claim Whitaker’s appointment is problematic because he was not confirmed by the Senate and thus was not “fully vetted” for possible conflicts of interests.

“The Attorney General is responsible for ensuring that we are a nation of laws and that every citizen and every government official — including the President himself — is equally subject to those laws,” the open letter published Tuesday reads. “Because of the profound responsibilities the position entails and the independence it requires, it can only be filled by someone who has been subjected to the strictest scrutiny under the process required by the Constitution.”

The letter, headed up by the non-partisan group Protect Democracy, asks the president to oust Whitaker for a “Senate-confirmed official who is next in the line of succession by operation of federal law.”

Said official would be Deputy Attorney General Rod Rosenstein, who was confirmed by the Senate in April 2017.

Last month, President Trump appointed Whitaker as acting Attorney General after firing then-Attorney General Jeff Sessions. Soon after Whitaker’s appointment, Democrat Senators filed a lawsuit in a district court to challenge the move, arguing it was unconstitutional because the Senate had not confirmed the official. “Installing Matthew Whitaker so flagrantly defies constitutional law that any viewer of School House Rock would recognize it,” Sens. Richard Blumenthal (D-CT), Sheldon Whitehouse, and Mazie Hirono (D-HI) said in a statement after filing the lawsuit.

Days later, Whitehouse wrote a letter to the Office of the Special Counsel investigate Whitaker for possible Hatch Act violations when the acting Attorney General served as chief of staff to Sessions.