The news that President Trump has fired FBI Director James B. Comey left me — it should leave all Americans — feeling more than mildly nauseous.

That was the memorable phrase Comey used last week to describe his feeling that his fateful letter to Congress about Hillary Clinton’s email might have influenced the election. Then, it was infuriating. Thanks, Director. Mildly nauseous? Some of us — maybe thanks to you — have woken up feeling that way every day since the election.

But firing an FBI director — now? With the bureau in the midst of an investigation that could determine the fate, political if not criminal, of the president who canned him?

To be clear: Like many people, I once was and no longer count myself a Comey fan. Reasonable people can differ about Comey’s July news conference, when he took it upon himself to state that no reasonable prosecutor would bring charges against Clinton but also to chide her for extreme carelessness in her handling of classified material. I thought the extraordinary circumstances of Bill Clinton’s tarmac visit with then-Attorney General Loretta Lynch, and the need to reassure the public of the completeness and impartiality of the investigation, justified Comey’s equally extraordinary public explanations.

But Comey’s preelection letter was nothing short of outrageous. It seemed more aimed at insulating Comey’s agency from criticism and — more to the point — burnishing his well-polished reputation for probity at the expense of electoral fairness.

(Bastien Inzaurralde/The Washington Post)

If I were president, I might have considered firing Comey myself.

Thus, the newly installed — and by all accounts, resolutely nonpartisan — deputy attorney general, Rod J. Rosenstein, had some undeniable points in his memorandum advocating Comey’s dismissal. Indeed, the FBI’s “reputation and credibility have suffered substantial damage” from Comey’s actions. As Rosenstein pointed out, there was “nearly universal judgment” among former Justice Department officials, Democratic and Republican appointees alike, that Comey’s intervention was an appalling departure from standard practice.

So if, say, President Barack Obama had fired Comey after the election, maybe even if Trump canned him after taking office, that would have been huge news. But not nauseating news. Not news that prompted, as did Tuesday’s action, words like “ Nixonian ” (Pennsylvania Democratic Sen. Robert P. Casey Jr.), charges of “coverup” (Senate Minority Leader Charles E. Schumer) and demands for an independent prosecutor.

Because firing Comey now is different. It is different because nothing significant has changed since Inauguration Day in terms of the reason cited for Comey’s firing — his handling of the Clinton emails. (Seriously, we are supposed to believe that the straw that broke Trump’s back was that Comey was inaccurate in his recent testimony and unfair to, of all people, Huma Abedin? Since when has inaccuracy been a problem for Trump?)

What has changed is that we now know the FBI is pursuing a serious investigation into Russian intervention in the election and potential entanglements with the Trump campaign, an investigation that could pose a mortal political, if not criminal, threat to Trump’s presidency.

Trump faced an unavoidable and escalating conflict in deciding Comey’s fate — a conflict that deepened with every presidential tweet dismissing the inquiry into Russian hacking and denigrating, explicitly or implicitly, the intelligence and law-enforcement agents who work for him. Tweets such as this, from Monday: “The Russia-Trump collusion story is a total hoax, when will this taxpayer funded charade end?” Remind me, who was overseeing this alleged charade?

Indeed, the untenable nature of Trump’s conflict was encapsulated in his own dismissal letter to Comey: “While I greatly appreciate you informing me, on three separate occasions, that I am not under investigation, I nevertheless concur with the judgment of the Department of Justice that you are not able to effectively lead the Bureau.”

Think about this, the sitting president of the United States announcing that he is not a crook — well, in his telling, not a suspected crook — as he fires the man who has been leading the investigation of his presidential campaign’s possible involvement with Russia.

If people aren’t buying Trump’s asserted rationale, it is because Trump made this bed of distrust. Nothing in his conduct offers comfort that he understands the importance of the independence of the Justice Department. (Remember, he was angry over Attorney General Jeff Sessions’s decision to recuse himself from the Russia probe.) Nothing suggests that he takes seriously the gravity of Russian intervention in the election or wants to get to the bottom of the mess.

Trump’s priority is, first and always, Trump. Which raises the question: Knowing, as he must have, that firing Comey would set off a firestorm, why did he calculate that this move was in his self-interest?

Read more from Ruth Marcus’s archive, follow her on Twitter or subscribe to her updates on Facebook.