US Attorney General Jeff Sessions has called for the resignation of 46 attorneys appointed by former president Barack Obama.
The demand was made in an announcement by the Department of Justice on Friday (10 March).
It is not unusual for attorneys appointed by former presidents to be asked to resign, with the change normally coming as the new administration takes over.
DOJ spokeswoman Sarah Isgur Flores said in a statement seen by The Hill: "As was the case in prior transitions, many of the United States attorneys nominated by the previous administration already have left the Department of Justice."
She explained that the prosecutors had been asked to resign by Sessions "in order to ensure a uniform transition" and said career attorneys would remain in their role until their successors were appointed.
However, the request has been criticised by Senate Democrat leader Charles Schumer who said that on previous occasions attorneys had been asked to submit resignation letters but were allowed to remain in their role "until their successor is confirmed".
"While it's true that presidents from both parties made their own choices for US attorney positions across the country, they have always done so in an orderly fashion that doesn't put ongoing investigations at risk," Schumer told The Hill.
"By asking for the immediate resignation of every remaining US attorney before their replacements have been confirmed or even nominated, the president is interrupting ongoing cases and investigations and hindering the administration of justice."
One attorney who was expected to remain in his role is Preet Bharara for the southern district of New York. Bharara has previously spoken to President Donald Trump and Sessions reportedly asked him to stay.
However, the resignations are not confirmed until Trump approves them.
Sessions stepped down from the investigation into alleged Russian interference in the US election when it was shown that he had lied to the Senate about his own meetings with the Russian ambassador in 2016.