Donald Trump and Robert Mueller.

By the standard that made Richard Nixon the historic figure he is today – the only president ever to resign to avoid certain impeachment and conviction – Special Counsel Robert Mueller’s probe of the Russian election interference and President Trump found no instantly dooming “smoking-gun” evidence.

Nixon, after all, was caught in the act by the sound of his own voice. Now historians and ordinary citizens can listen to the evidence that became known as Nixon’s “smoking gun” tape – captured for history on his own secret recording system. We can hear Nixon ordering his top advisers to obstruct justice by deceiving the FBI into halting its probe of the Nixon team’s burglary of the Democratic Party’s headquarters at the Watergate building. Just hours after we learned of that tape recording, even Nixon’s most loyal senior Republicans told him he had to go.

But for all the outrageous things we’ve heard Trump say – and all of his bizarre tweets we’ve read – the most damaging thing to befall America’s 45th president may be Mueller’s meticulous reconstructing of Trump’s persistent behind-the-scenes efforts to obstruct the FBI’s and special counsel’s investigations of Russia’s interference in our election.

After Trump’s very public firing of FBI Director James Comey, Mueller chronicled how Trump was unnerved and enraged by Deputy Attorney General Rod Rosenstein’s May 2017 naming of former FBI chief Mueller to be special counsel investigating Russia’s election interference and possible Trump campaign ties. Mueller’s report said Trump slumped in his chair and said: “Oh my God. This is terrible. This is the end of my presidency. I’m f----d.”

Trump immediately sought on several occasions to get his White House Counsel Don McGahn to oust Mueller in a way that wouldn’t seem like it was Trump’s doing.

“On June 17, 2017,” Mueller wrote, “the President called McGahn at home and directed him to call the Acting Attorney General and say that the Special Counsel had conflicts of interest and must be removed. McGahn did not carry out the direction, however, deciding that he would resign rather than trigger what he regarded as a potential Saturday Night Massacre.”

Mueller also made clear that he thought Trump had a deeper motive for fearing an unfettered investigation of Trump’s ties to Russia. “...the President had a motive to put the FBI’s Russia investigation behind him,” Mueller’s report said. “...the evidence does indicate that a thorough FBI investigation would uncover facts about the campaign and the President personally that the President could have understood to be crimes or that would give rise to personal and political concerns.”

It is worth noting that you have just read what Trump’s carefully chosen new Attorney General, William Barr, read days ago, when he decided to declare that the evidence in Mueller’s report did not constitute a crime of obstruction of justice. Remember that Barr had told us he made that decision because Mueller had said he would make no decision on whether or not that constituted a crime.

Here’s what Mueller’s report actually tells us about that: “The evidence we obtained about the President’s actions and intent presents difficult issues that prevent us from conclusively determining that no criminal conduct occurred.”

Mueller also devoted an entire section to his suggestion that the question of whether Trump obstructed justice was a matter Congress had the authority to consider. Among his points was the fact that, by past Justice Department guidance, presidents cannot be indicted, but they can be impeached, or Congress can take other action to clarify that matter.