The U.S. State Department's entire senior management team has left the department, and reports were conflicting about whether they resigned or were forced out.

The Washington Post, citing State Department officials, first reported that all four officials resigned voluntarily. CNN, citing senior administration officials, were asked to leave. Regardless, the departures complicate Rex Tillerson's job should he get confirmed to lead the department.

"It's the single biggest simultaneous departure of institutional memory that anyone can remember, and that's incredibly difficult to replicate," David Wade, the State Department's chief of staff under Secretary of State John Kerry, told the Post. "Department expertise in security, management, administrative and consular positions in particular are very difficult to replicate and particularly difficult to find in the private sector."

At least one of the officials who resigned was hoping to keep his post under the new administration, according to the Post's story. CNN's report said the firings were part of an effort to "clean house" at the department.

Incoming secretaries of state typically vet many senior officials to see which ones they would like to keep. The departing staffers, according to the Post and CNN, are: