President Trump poses with Russian Foreign Minister Sergei Lavrov during a meeting at the White House in Washington in May 2017. (Russian Foreign Ministry via AFP/Getty Images)
Opinion writer

President Trump, for reasons not immediately evident, tweeted this morning: “Not that it matters but I never fired James Comey because of Russia! The Corrupt Mainstream Media loves to keep pushing that narrative, but they know it is not true!” One wonders whether a conversation with one of his lawyers or a “Fox & Friends” discussion about obstruction of justice might have prompted such a self-serving tweet. The good news for the rule of law and our national sanity is that Trump’s lies arguably make things worse for him.

Two days after firing James B. Comey as FBI director, Trump told NBC News’ Lester Holt: “And, in fact, when I decided to just do it, I said to myself, I said: ‘You know, this Russia thing with Trump and Russia is a made-up story. It’s an excuse by the Democrats for having lost an election that they should’ve won.'” Moreover, on the day after he fired Comey, Trump in the Oval Office allegedly told the Russian foreign minister and ambassador: “I faced great pressure because of Russia. That’s taken off.”

Since we know Trump is incapable of editing himself, he almost certainly has expressed to White House aides his annoyance with Comey’s pursuit of the Russia investigation. Those aides surely will have been interviewed by the time special counsel Robert S. Mueller III completes his reports. Mueller also should have the original draft of Trump’s letter terminating Comey. The Post reported on that letter last September:

The multi-page letter blasted Comey over his investigation of Trump’s Democratic presidential opponent, Hillary Clinton. And, according to a person with direct knowledge of the contents of the letter, it conveyed Trump’s displeasure that Comey would not say publicly what he had told the president three times privately: that the FBI’s probe into Russia’s interference in the 2016 election was not focused on him.

Trump ended up shelving that letter in favor of a far shorter one, but the draft has taken on new significance in the probe by special counsel Robert S. Mueller III, who is examining it as he determines whether Trump’s firing of Comey was part of an effort to obstruct justice, according to people with knowledge of the investigation.

As a practical matter, Trump’s contemporaneous writings and comments will settle the issue of his “corrupt intent.” Rather than muddy the issue, Trump continues to display a pattern of obstruction, which includes cooking up phony excuses for firing Comey and, as he did in the Thursday morning tweet, trying to edit out incriminating statements. In other words, his current lies are further evidence to support a possible charge of obstruction of justice. Moreover, given how important his intent is to establishing a possible crime, Trump only strengthens the rationale for Mueller’s interview.

Trump’s revisionist history might provide himself and his cultist followers with temporary comfort. Trump is infamous for inventing his own reality — and his apologists are infamous for swallowing whatever he puts out, no matter how untethered to reality or self-contradictory his statements are. The mainstream media’s job is to report the current statement and the contradictory statements so that the rest of the public can see for itself Trump’s pattern of deception.

The only audience that really matters is Mueller. He is likely collecting a pile of evidence, much of it unknown to Trump, to piece together a picture of an ongoing effort to obstruct the Russia investigation. Mueller can slot the latest tweet into place. For voters, Trump’s constant lies may be infuriating; for Mueller, they should be an embarrassment of evidentiary riches.