His investigators, Trump declared, “cannot believe what they’re finding”.

I can find no record of Trump being challenged on this outlandish claim at the time. In the autumn of 2016, Trump, now the Republican presidential nominee, was convinced by his staff that he had to abandon this “birther” nonsense.

He did so reluctantly, charging — also with no evidence — that such rumours had actually been initiated by his opponent, Hillary Clinton.

There, in a nutshell, is Trump’s modus operandi: he’s not just a liar but a fabulist, seemingly unconcerned with whether his fictions will be exposed. If they are, the world simply moves on as he invents fresh distractions.

Another distinctive trait of Trump’s presidency has been his systematic effort to dismantle the guard rails that are intended to limit executive power. The most recent example has been the firing of four inspectors-general, a genus of civil servant created after Watergate to act as independent checks on the conduct of federal agencies and their officials.

Trump fired the acting inspector-general in the US department of health and human services after her office reported a serious shortage of crucial equipment to fight the Covid-19 pandemic.

Trump was even more eager to get rid of her when he learned she had worked in Barack Obama’s administration, though she first joined the department during Bill Clinton’s presidency. In fact, Trump recently suggested that all the inspectors-general may be Obama-era holdovers — and therefore should be fired.

Moreover, Trump’s fury over the investigation of his 2016 election campaign’s dealings with Russia and his impeachment in January — subjects that trigger his rage and vindictiveness — is still playing out.

Virtually anyone involved in either episode is vulnerable. Two of the recently fired inspectors-general fall into those categories.

Trump is usually too angry a man to stop before he harms himself, unless his aides persuade him otherwise. But his current aides, on the whole, aren’t as strong as before, and Trump is more confident in his own instincts. (He isn’t the first president to say to an aide: “I’m president and you’re not.”) And he’s getting a lot closer to an election that he could lose.

Now, Trump is bent on discrediting the Russia investigation itself, which he has always deemed a “hoax” and “fake news”.

So, with the aid of a cooperative attorney general, William Barr, he has set out to “prove” that there was no basis for launching it.

When Barr took over the US Justice Department in February 2019, he made it clear that he saw his job as being Trump’s defender and advocate. And Trump, who has no concept of public service, had become convinced that the federal government was composed of a “deep state” bent on destroying his presidency.

This explains a lot of what has happened.

Trump fired FBI director James Comey, who had resisted the former’s blandishments that he was to be the president’s subordinate, only to find himself facing a special counsel, Robert Mueller, appointed by the Justice Department.

As far as Trump was concerned, Barr had to rein in the department.

The complaisant Barr took actions that damaged both the president and himself.

He had his prosecutors intervene to reduce a court sentence for Trump’s longtime political associate Roger Stone, prompting four federal prosecutors who had tried the case to resign.

After the outcry among justice department employees died down, Barr even more flagrantly arranged for federal prosecutors to move to drop the charges against retired Lt General Michael Flynn, the first of Trump’s four national security advisers (so far).

Flynn who had twice admitted under oath to lying to the FBI about his secret conversations during the transition with the Russian ambassador to the US, Sergey Kislyak, and Trump fired him because he had also lied to vice president Mike Pence about these talks.

The move to drop the charges against Flynn led to the resignation of the case’s lead prosecutor and an uproar among established lawyers, both Republican and Democrat, who called on Barr to resign.

The trial court judge in the Flynn case made the highly unusual decision to appoint an outside counsel to argue in court in June against Justice’s move to withdraw the charges.

The erratic Flynn, a registered Democrat (Trump’s “lock her up” campaign slogan against Clinton notwithstanding), had been an admired intelligence officer in Afghanistan, but he needed level-headed supervision to temper his wilder conclusions.

After he was promoted to head the Defense Intelligence Agency, he floundered, leading Obama to fire him. Obama also advised Trump not to hire him as national security adviser.

Flynn’s resulting bitterness toward Obama makes him a useful instrument in Trump’s latest plot: to destroy his popular predecessor’s standing as an advocate for former vice president Joe Biden, Trump’s presumptive opponent in this year’s election.

But, for Flynn to be useful, he can’t be a convict, and the charges regarding his calls to the Russian ambassador must be expunged in order to claim that there was no basis for the Mueller investigation.

On May 15, Trump claimed in a tweet that Obama, who ran one of the cleanest administrations in decades, had participated in “the greatest political scandal in the history of the US”.

But Trump has yet to say just what “Obamagate” is.

Has Trump finally spun a fable that he can’t get away with? Barr, now expressing concern that the justice department can’t be “political,” has just said that Obama and Biden won’t be prosecuted, taking Trump by surprise.

With 100,000 in the US expected to have died from Covid-19 by June 1, and with unemployment soaring to more than 33 million, American voters are more likely to be more interested in their health, safety, and jobs than anything Flynn has to say about Obama.

Elizabeth Drew is a Washington-based journalist and the author, most recently, of Washington Journal: Reporting Watergate and Richard Nixon’s Downfall. Copyright: Project Syndicate, 2020.