The challenge, filed by Maryland Attorney General Brian Frosh Tuesday, argues that the appointment violates the succession statute, which gives the deputy attorney general full authority should the attorney general position become vacant. Frosh also argues the appointment violates the constitution’s appointment clause, requiring that presidential appointments be confirmed by the senate.

The legal challenge argues that an injunction is warranted and calls on deputy attorney general Rod Rosenstein to replace him.

“The Attorney General’s succession statute and the Constitution protect the country against exactly what President Trump has attempted to do here—pluck an unqualified and unconfirmed partisan to be the nation’s chief law enforcement officer in order to protect the President personally rather than the rule of law,” Frosh said in a statement. “President Trump’s brazen attempt to flout the law and Constitution in bypassing Deputy U.S. Attorney General Rosenstein in favor of a partisan and unqualified staffer cannot stand.”

The challenge was filed as a motion as part of an ongoing lawsuit against the federal government that seeks to uphold protections of people with preexisting conditions and other provisions of the Affordable Care Act.

Amid pressure from Trump, Jeff Sessions resigned on Nov. 7, the day after midterm elections shifted power in the House to the Democratic Party. Sessions, an early supporter of Trump, lost the president’s favor when herecused himself from the investigation into Russian interference in the 2016 presidential election.

In his new role, Whitaker oversees the investigation, though Whitaker’s past public statements on the investigation suggest that he is already ethically compromised.