Several Senate Democrats are suing to challenge the appointment of Matt Whitaker as acting attorney general, arguing that it stands in violation of the U.S. Constitution.

Sens. Richard Blumenthal (D-CT), Mazie K. Hirono (D-HI) and Sheldon Whitehouse (D-RI) are behind the suit, which was filed in the U.S. District Court for the District of Columbia, The Daily Beast first reported. The Senators are represented by the nonpartisan law firms Protect Democracy and the Constitutional Accountability Center.

This marks the second legal challenge to Whitaker’s appointment by President Donald Trump. The state of Maryland asked a federal judge for an injunction last week, claiming that Whitaker’s placement was unconstitutional – as he had not been confirmed by the Senate – and that it contradicts the Attorney General Succession Act, which designates the statutory order of succession in the Department of Justice should there be a vacancy in the nation’s chief law enforcement role. Ultimately, Maryland wants the judge to declare Whitaker’s appointment as illegitimate – and that the post rightfully belongs to the current deputy attorney general, Rod Rosenstein.

The Justice Department’s Office of Legal Counsel fired back, issuing a memo defending Whitaker’s appointment and Trump’s powers to install him. “This Office had previously advised that the President could designate a senior Department of Justice official, such as Mr. Whitaker, as Acting Attorney General,” the memo said.

The latest suit from Senate Democrats echoed Maryland’s, arguing that Whitaker’s placement violates the Constitution’s Appointments Clause, as he had not occupied a Senate-confirmed position in his prior post. Whitaker served as chief of staff to former Attorney General Jeff Sessions, who was fired by the president the day after the midterm elections.

“Donald Trump cannot subvert the Constitution to protect himself and evade accountability,” Hirono said in a statement. “We want the court to make clear that the Senate must confirm Matthew Whitaker’s appointment as Acting Attorney General – otherwise this temporary appointment violates the Constitution’s Appointment Clause.”

Trump installed Whitaker via the Vacancies Reform Act, where a person can be appointed by the president for a vacant post for up to 210 days. “But many constitutional scholars have argued that the Vacancies Reform Act doesn’t let the president appoint people to cabinet-level positions who haven’t been Senate confirmed,” according to The Daily Beast. “The Senate confirmed Whitaker in 2004 as a U.S. Attorney in Iowa, but his opponents – most prominently George Conway, the husband of White House senior staffer Kellyanne Conway, and former Solicitor General Neal Katyal – say that confirmation has effectively lapsed.”

“Installing Matthew Whitaker so flagrantly defies constitutional law that any viewer of Schoolhouse Rock would recognize it,” Blumenthal said in a statement. “President Trump is denying Senators our constitutional obligation and opportunity to do our job: scrutinizing the nomination of our nation’s top law enforcement official. The reason is simple: Whitaker would never pass the advice and consent test. In selecting a so-called ‘constitutional nobody’ and thwarting every Senator’s constitutional duty, Trump leaves us no choice but to seek recourse through the courts.”

Americans prize checks & balances. Trump’s dictatorial appointment of Whitaker denies Senators from completing our constitutional obligation to scrutinize the nomination of our top law enforcement official. We are left with no choice but to seek recourse through the courts. pic.twitter.com/dUrCZRFYUs

— Richard Blumenthal (@SenBlumenthal) November 19, 2018

Once Sessions recused himself from the Russia investigation into the Trump campaign, the president had waged public attacks on his character, making his ouster seem inevitable. Trump announced Whitaker as acting attorney general in the same tweet where he declared Sessions’ resignation. But what troubled many people beyond Whitaker’s lack of Senate confirmation was that he had publicly undermined the Russia investigation in op-eds and as a TV pundit. Whitaker once said in an interview on the “Wilkow Majority Show” that there “was no collusion with the Russians and the Trump campaign” in 2017, even though Robert Mueller’s inquiry is still not completed. A few months later, Whitaker wrote an article for CNN with the title: “Mueller’s investigation of Trump is going too far.”

Whitaker now oversees the Justice Department – and the very investigation he has publicly criticized. “The stakes are too high to allow the president to install an unconfirmed lackey to lead the Department of Justice – a lackey whose stated purpose, apparently, is undermining a major investigation into the president,” Whitehouse said in the statement. “Unless the courts intercede, this troubling move creates a plain road map for persistent and deliberate evasion by the executive branch of the Senate’s constitutionally mandated advice and consent. Indeed, this appointment appears planned to accomplish that goal.”