The Justice Department made the announcement on Friday, saying that the move was in accord with tradition. Of the total 93 attorneys, 46 remain from the Obama administration.
“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,” said DOJ spokeswoman Sarah Isgur Flores.
While replacing US attorneys at the beginning of new administrations comes as no surprise, the decision to immediately ask all of the federal prosecutors to resign has raised some questions.
Surprisingly, the resignation call also includes Preet Bharara, the US attorney for the Southern District of New York.
Bharara and Trump reportedly met after the November 8 election and the New York attorney agreed to remain in his position throughout the Trump administration. The prosecutor told The New York Times that Sessions also asked him to stay.
The resignation letters will be reviewed by Trump, who then determines whether they should all be accepted.
Senate Democratic leader Chuck Schumer, a fierce Trump critic, said he was "troubled” by the decision, saying it would harm the ongoing investigations.