We have never seen such hatred and obsessiveness by any President against a predecessor or successor in the Oval Office or a presidential rival as we see with Donald Trump’s attitude toward Barack Obama and Hillary Clinton.
There have been other rivalries that existed, as for instance:
John Adams and Thomas Jefferson;
John Quincy Adams and Andrew Jackson;
Theodore Roosevelt and William Howard Taft;
Theodore Roosevelt and Woodrow Wilson;
Herbert Hoover and Franklin D. Roosevelt;
Harry Truman and Dwight D. Eisenhower;
Harry Truman and Richard Nixon;
Richard Nixon and Nelson Rockefeller;
Jimmy Carter and Ronald Reagan
as the major cases, but none of these rivalries were on the level of Donald Trump with Barack Obama and Hillary Clinton.
None of these was a situation of such vehement, long lasting venom, and the manufacturing of lies and accusations that are clearly paranoid and vicious to an extreme, with no possibility of being resolved.
Some of the above rivalries were long lasting, including JQ Adams and Jackson, TR and Wilson, and Hoover and FDR, but the rest ended up with reconciliation and eventual communication between the two parties involved.
That will never happen with Donald Trump, and it is a sad commentary that teaches the wrong lessons to children and to all of us, that no matter what differences one has, they can be overcome with a real effort and commitment.
The difference is that Donald Trump, unlike past Presidents, is clearly a person with a serious mental illness, which undermines the possibility of cooperation among and unity of the American people.