“This White House appears to be cannibalizing itself,” said William C. Inboden, a former national security aide to President George W. Bush. “While many previous White House staffs have feuded with each other and leaked against each other, this is the first time in history I am aware of a White House openly attacking its own staff — especially for merely upholding their constitutional duties.”

In part, that reflects the challenge for a president facing an impeachment inquiry where every witness called so far either currently or previously worked in the government over which he presides. To defend against potential charges of high crimes and misdemeanors, Mr. Trump evidently feels he must undercut the believability of the witnesses testifying about his pressure campaign on Ukraine for help against his domestic rivals.

It also reflects the president’s longstanding distrust of the career professionals who populate his White House, just as they have every other. While such officials characterize their work as nonpartisan in service of presidents of either party, Mr. Trump has felt burned since the early days of his administration when internal documents were leaked, including transcripts of two of his phone calls with foreign leaders.