NBC News carried the report on Friday, citing Defense Department officials.
The network reminded that it was not uncommon for administration officials to prepare such letters towards the end of each administration’s tenure as this would give the next president an opportunity to potentially reinstate them in office.
However, the report cited the officials as saying that Esper had written his letter “because he is one of the Cabinet officials long expected to be pushed out after the election.”
The report also pointed to a history of rifts between the defense chief and the chief executive, including in the case of Trump’s insistence on using the military to suppress street protests.
It also referred to a plan by Esper to strip military bases of names of Confederate figures -- which echo the United States’ long history of racism and slavery -- as another sticking point between the two.
Last month, the Axios news and information website said Trump planned to fire a number of officials upon potential releection.