To understand what happens next with Donald Trump – now that his personal lawyer Michael Cohen has been sentenced to jail and is apparently threatening to drop the bucket on the President’s head – you need to look back six months. And then 45 years.

In early June, Mr Cohen was expecting to be arrested and seemed to be wavering in his “take a bullet” loyalty to the President. For his part, Mr Trump was building himself up and declared himself untouchable.

On June 4, he tweeted: “As has been stated by numerous legal scholars, I have the absolute right to PARDON myself, but why would I do that when I have done nothing wrong?”

As has been stated by numerous legal scholars, I have the absolute right to PARDON myself, but why would I do that when I have done nothing wrong? In the meantime, the never ending Witch Hunt, led by 13 very Angry and Conflicted Democrats (& others) continues into the mid-terms!

— Donald J. Trump (@realDonaldTrump) June 4, 2018

At that time, Mr Trump’s lawyers, Jay A. Sekulow and John M. Dowd, in a memo to special prosecutor Robert Mueller that attempted to shut down the Russia investigation – argued that, as The New York Times put it: “The President cannot obstruct justice, because he is the arbiter of justice.”

Mr Trump’s attorney Rudolph Giuliani went even further by saying that Mr Trump couldn’t be subpoenaed or indicted while in office, even if he’d shot the former FBI director James Comey – such was the mightiness of the President’s constitutional powers.

At the time, the liberal press reacted with scorn.

Now that Mr Cohen has been jailed for three years, in part for breaking campaign finance laws on behalf of – and apparently in concert with Mr Trump – commentary is rich with speculation and righteous anticipation.

There is a feeling that something big is going to happen – but nobody is sure what it is. And that goes for Mr Trump himself. It’s this not knowing that must be driving Mr Trump nuts.

As The Atlantic noted when Mr Cohen, two weeks ago, first pleaded guilty to lying to Congress, the remarkable thing – in the age of constant leaks – was that nobody outside the of the closeted investigation saw it coming.

“Cohen’s plea, a momentous development in Special Counsel Robert Mueller’s investigation, happened with no warning. That reflects admirable discipline in Mueller’s office,” wrote former federal prosecutor Ken White.

Watch Mr Cohen’s interview with ABC News

So what’s next?

Firstly, less attention is being paid to the admission by American Media Inc. (AMI), the parent company of National Enquirer, that it helped facilitate hush payments to former Playboy model Karen McDougal and has agreed to cooperate with the ongoing investigation being run by the Southern District of New York.

As the prosecutor’s office said in a press release: “AMI admitted that it made the $US150,000 payment in concert with a candidate’s presidential campaign, and in order to ensure that the woman did not publicise damaging allegations about the candidate before the 2016 presidential election.”

This puts Mr Trump right in it.

But it’s been overshadowed by the giddy speculation as to what Mr Cohen will reveal next. Again it’s this not knowing that has Mr Trump and his critics – let’s just call them opponents – sitting on the edge of their seats.

As Mr Cohen’s former lawyer Lanny Davis told Vanity Fair: “He can be the next generation of what John Dean was to Richard Nixon. He should be sitting in front of a congressional committee and telling the truth the way that John Dean did.”

Mr Dean was the counsel who was jailed for four months for his part in the Watergate scandal – but was publicly rehabilitated after testifying against Mr Nixon.

Mr Dean went on to live a brand new life in which he walked tall.

Michael Cohen, longtime personal lawyer and confidante for President Donald Trump, leaves US District Court Southern District of New York in April. Photo: Getty

Mr Cohen is making noises about going the same way.

In a post-sentencing interview with George Stephanopoulos on US network ABC, Mr Cohen said: “And one of the hopes that I have out of the punishment that I’ve received, as well as the cooperation that I have given, I will be remembered in history as helping to bring this country back together.”

Mr Trump has responded to Mr Cohen’s conviction and sentencing with a series of punishing tweets, including an obscure reference to Mr Cohen’s family being temporarily off the hook, that have only served to deepen Mr Cohen’s resolve.

“I took responsibility for my actions. And instead of him taking responsibility for his actions, what does he do?” he said. “He attacks my family. And after yesterday, again being before the court and taking the responsibility and receiving a sentence of 36 months, the only thing he could do is to tweet about my family?”

He goes further, in what seems to be a direct message to Mr Trump.

He knows the truth. I know the truth … I am done with the lying. I am done being loyal to President Trump, and my first loyalty belongs to my wife, my daughter, my son and this country … I will not be the villain of his story.”

At the moment, Mr Cohen’s talk of seeking a brand-new start may seem like one more dirty rat suddenly, conveniently, finding Jesus. But there’s clearly personal animosity now at work.

Consider these words, Mr Cohen’s response to a Trump tweet that called him weak: “It was my blind loyalty to this man that led me to take a path of darkness instead of light. I felt it was my duty to cover up his dirty deeds.”

We’re yet to hear what those all deeds were. It doesn’t matter what Mr Tump has to say about it, what claims he makes to immunity.

It’s the quality of dirt we’re counting on – and the not knowing is what makes the wait so thrilling.