The White House's decision to decline the release of those emails follows a precedent set by presidents of both parties that keeps presidential communications secret until after the president has left office, officials say, noting that the decision was not made based on the contents of the emails.

"There is a long history of presidential records being kept confidential while the president is in office," one White House official says. "It is a principle that previous White Houses have vigorously defended as it goes to the core of the president’s ability to receive unvarnished advice and counsel during his time in office and is central to the independent functioning of the Executive Branch."