US Attorney General Jeff Sessions is asking for the resignations of 46 attorneys hired by former president Barack Obama, the Justice Department said Friday.
Many of the federal prosecutors who were nominated by Mr Obama have already left their positions.
But the 46 who stayed on in the first weeks of the Donald Trump administration have now been asked to leave "in order to ensure a uniform transition," Justice Department spokeswoman Sarah Isgur Flores said.
"Until the new US attorneys are confirmed, the dedicated career prosecutors in our US attorney's offices will continue the great work of the department in investigating, prosecuting and deterring the most violent offenders," she said in a statement.
It is customary, though not automatic, for the country's 93 US attorneys to leave their positions once a new president is in office.
The Obama administration allowed political appointees of President George W Bush to serve until their replacement had been nominated and confirmed.
The federal prosecutors are nominated by the president, generally upon the recommendation of a home-state senator.
One US attorney appointed by Bush, Rod Rosenstein of Maryland, remained on the job for the entire Obama administration and is the current nominee for deputy attorney general.
US attorneys are responsible for prosecuting federal crimes in the territories they oversee. They report to Justice Department leadership in Washington, and their priorities are expected to be in line with those of the attorney general.