"It bothers me that a president of the United States, instead of accepting responsibility for what he does and what his administration does, constantly looks for other scapegoats, whether it's Congress, whether it's past presidents, whether it's somebody else," said Leon Panetta, who served as defense secretary under Obama. "He is never responsible for anything that goes wrong. And the reality is the American people understand that presidents make mistakes."

Dormant, for now, is the long-running custom of informal consultation between the occupant of the White House and its previous inhabitants. Trump hasn't contacted Jimmy Carter, George H.W. Bush, Bill Clinton, George W. Bush or Obama to discuss the myriad world crises he faces, despite their experience in comparable circumstances.

The chasm between Trump and his predecessors is another data point in an untraditional presidency, one that has discarded many of the unwritten rules and customs that used to dictate how presidents behave.