WASHINGTON (Reuters) - A Russian company accused of helping fund a propaganda operation to sway the 2016 presidential election in Donald Trump’s favor asked a federal judge on Monday to dismiss charges brought by Special Counsel Robert Mueller, saying Mueller was unlawfully appointed and lacks prosecutorial authority.

FILE PHOTO: Evgeny Prigozhin (L) assists Russian Prime Minister Vladimir Putin during a dinner with foreign scholars and journalists at the restaurant Cheval Blanc on the premises of an equestrian complex outside Moscow November 11, 2011. REUTERS/Misha Japaridze/Pool/File Photo

Concord Management and Consulting LLC, a firm that prosecutors say is controlled by a businessman dubbed by Russian media as “Putin’s cook,” argued in a filing in U.S. district court in Washington that Deputy Attorney General Rod Rosenstein violated the Appointments Clause of the U.S. Constitution when he hired Mueller in May 2017.

Concord is one of three entities, along with 13 Russian individuals, indicted by Special Counsel Robert Mueller’s office in February in an alleged criminal and espionage conspiracy to tamper with the U.S. race, boost Trump and disparage his Democratic opponent, Hillary Clinton.

The indictment said Concord is controlled by Russian businessman Evgeny Prigozhin, who U.S. officials have said has extensive ties to Russia’s military and political establishment.

In it, Concord is alleged to have controlled funding, recommended personnel and overseen the activities of the propaganda campaign.

Concord is the only one of the defendants in the case to have formally responded to the charges in federal court. Earlier this year, it hired American lawyers to fight the indictment.

Under the Constitution’s Appointments Clause, principal officers such as cabinet secretaries are appointed by the president and confirmed by the United States Senate while “inferior officers” may be appointed by courts or department heads if permitted by Congress.

Concord’s lawyers say that Mueller qualifies as an “officer” under the clause and not a routine federal employee under the law because of his vast prosecutorial authority.

They say that no matter whether Mueller is deemed an “inferior” or “principal” officer, his appointment still violates the Constitution.

As a principal officer, they say, he should have been appointed by the president and confirmed by the Senate.

But even if a court disagreed and ruled that Mueller was an inferior officer, they say, his hiring is still unlawful because Rosenstein lacked “express and specific statutory authorization” from Congress.

That legal argument is similar to one put forth last month by Steven Calabresi, co-founder of the conservative Federalist Society, who in a call with journalists and lawyers said that all of Mueller’s actions are illegal because he was improperly appointed.