The new review, according to intelligence officials, is designed to reduce duplication among the Office of the Director of National Intelligence, the C.I.A. and other agencies. It would also send intelligence officers assigned to the director back to their home agencies, with the view that those agencies could better allocate them.
While the decision on the review will be up to Mr. Grenell, Gina Haspel, the C.I.A. director, is generally supportive, given that the study could send agency officers back to its headquarters in Langley, Va., according to people briefed on her view.
The proposals remain in early stages, though Mr. Grenell has signaled that he wants to move quickly because his time in office is limited.
Kashyap Patel, an aide in the director’s office who was transferred last month from the White House, is involved in the review, according to people familiar with the matter. Mr. Patel was a former aide to Representative Devin Nunes, Republican of California, who has long argued that the intelligence office should be pared back.
Mr. Patel’s arrival has been greeted skeptically in the headquarters of the director of national intelligence, known as Liberty Crossing. Some officials have said that they believed Mr. Grenell and Mr. Patel were sent by the White House to purge the ranks of intelligence officers disloyal to Mr. Trump.
“The White House, the president doesn’t see the need for O.D.N.I.,” said James R. Clapper Jr., a former director of national intelligence who has been sharply critical of Mr. Trump. “So I would infer that Grenell’s marching orders were to cut the place.”
A debate has long churned about whether the office has grown too large, but Mr. Trump’s longstanding skepticism of his intelligence agencies has sown suspicion that the administration may be conducting the review for partisan purposes.