It will be only the third time in US history and while its outcome looks preordained, it will doubtless be high political drama. Foreign Editor David Pratt runs an eye over the cast and script for Trump’s impeachment

This coming Thursday an update on the “Doomsday Clock” is scheduled to be announced at a news conference in Washington. For those unfamiliar with this iconic timepiece, it symbolises how close humanity is to the apocalypse.

Ever since the end of the Second World War, a body known as the Bulletin of the Atomic Scientists have dedicated themselves to equipping the world with the information needed to reduce manmade threats to our existence.

According to their reckoning, currently the clock is set at two minutes to midnight, the closest it has been to the “doomsday” hour since the height of the Cold War arms race.

Should the minute hand on the clock creep forward on Thursday, then no doubt there will be those inclined to attribute such a dangerous escalation, in part, to recent volatile events in the Middle East and the man responsible, US President Donald Trump.

Not that any of this will catch Trump’s attention for a second. For this week he will have much bigger things on his mind than the end of the world, as we know it.

I’m referring, of course, to that other far more “important” existential threat to Trump looming in Washington this week: the start of his impeachment trial.

It was last Thursday that the Senate impeachment on whether to remove the president from office formally got under way.

Wearing his black judicial robe, Chief Justice John Roberts presided over the swearing in of the senators who pledged to deliver impartial justice, and the formal reading of the two charges levelled at Trump – abuse of power and obstruction of Congress.

Only hours before the senators took their oaths, the nonpartisan US Government Accountability Office (GAO), a watchdog agency, determined that the White House broke the law when it withheld congress approved aid to Ukraine, one of the issues at the heart of the impeachment case against the president.

The GAO said the US Constitution does not grant a president authority to unilaterally withhold funds, as Trump did. Instead, a president can only withhold spending in limited circumstances spelled out by law, its report said.

The abuse of power cited in the House articles of impeachment included Trump’s withholding of $391 million in security aid for Ukraine, a move Democrats have said was aimed at pressuring Kiev into investigating political rival Joe Biden, the president’s possible Democratic opponent in the coming November 3 election.

Congress had approved the funds to help Ukraine combat Russia-backed separatists. The money was ultimately provided in September after the controversy spilled into public view. Meantime, the political fallout from this murky affair has been enormous, resulting in only the third impeachment trial in US history.

In that time, no president has been removed as a direct result of the process. Richard Nixon resigned in 1974 before the full House could vote to impeach him. The House impeached Andrew Johnson in 1868 and Bill Clinton in 1998, but the Senate did not convict them.

In Trump’s case, the Senate will most likely acquit him given that none of its 53 Republicans has voiced support for removing him, a step that requires a two-thirds majority.

This, however, will not stop the trial unfolding as an astonishing piece of American political drama for which the colourful cast is already being mustered. These past few days “Team Trump” was finally being confirmed with the president turning to the lawyer who led the effort to unseat Bill Clinton two decades ago as part of a heavyweight legal team to defend him as the trial begins in earnest on Tuesday.

Former independent counsel Ken Starr was chosen, as was Robert W Ray, his successor as independent counsel. Joining the line-up, too, will be celebrity lawyer Alan Dershowitz, the Harvard law professor who successfully defended Claus von Bulow and OJ Simpson in murder trials that gripped the US. Dershowitz will be joined by other prominent attorneys led by Pat Cipollone, the White House counsel, and Jay Sekulow, one of Trump’s personal lawyers.

But according to a number of White House watchers, while Trump sees his “team” as a safe pair of hands, they almost all come with a downside.

“In choosing the three prominent lawyers, the president assembled what he regards as an all-star television legal team, enlisting some of his favourite defenders from Fox News,” observed the New York Times.

“But each of them brings his own baggage. Mr Dershowitz represented Jeffrey Epstein, the convicted sex offender. Mr Starr was pushed out as a university president because of his handling of sexual misconduct by the football team. And Mr Ray was once charged with stalking a former girlfriend,” two of the newspaper’s chief White House correspondents observed, writing on Friday.

For her part, Nancy Pelosi, the Democratic speaker of the House, announced on Wednesday her picks for what Politico magazine called “the most sought-after jobs on Capitol Hill: impeachment manager”.

These seven House Democrats will prosecute the case against Trump. They are Adam Schiff of California, Jerrold Nadler of New York, Zoe Lofgren of California, Hakeem Jeffries of New York, Val Demings of Florida, Jason Crow of Colorado, and Sylvia Garcia of Texas.

According to Politico, Pelosi’s list “reflects her desire for geographic, racial and gender diversity among the impeachment managers, and it draws from the Democratic Caucus’ wide swath of legal and national security-related experience”.

By far the most significant among those on the list, of course, is House Intelligence Committee chairman Schiff, who over the years has established a reputation as public enemy number one for Trump and his allies.

To Trump and millions of his loyalists, it’s now “Shifty Schiff” though other insults are common with “liar” and “traitor” often making appearances on social media. The relentless doing down of Schiff has also given an added bonus to the finances of Trump’s presidential re-election hopes with $34 going into the campaign coffers for every “Pencil-Neck Adam Schiff” T-shirt sold.

Not to be outdone, some Democrats now wear “I Stand With Schiff” T-shirts. His supporters’ response even attempts to own the Trump put-downs. Pencils labelled “This Pencil Neck Won’t Break” and “This Pencil Neck Will Investigate” go for $8 a pack.

But as the Los Angeles Times has noted, Schiff’s rise to become Trump’s popular political nemesis has taken time and the route been convoluted to say the least.

The newspaper describes him as a “self-improvement obsessive who earned a brown belt in karate, dabbled in Slovak and wrote screenplays before he committed fully to politics. His early academic career initially had him on a path to medicine before he earned his law degree from Harvard Law School. It is precisely that sharp legal training, however, that Pelosi and other democrats are hoping will be brought to bear at Trump’s expense during the trial.

Many say Schiff, who has called Trump the worst US president in modern history, now has the political bit between his teeth and will be undaunted by the formidable legal team the president has assembled in his defence.

“They can try to scream at him. They can try to run him out of the room, but it’s not going to work,” said Barbara Boxer, the former senator from California, who encouraged Schiff to run for his House seat 20 years ago. “The moment has really found him, and he is ready,” Boxer was quoted by the Los Angeles Times as saying.

And what a moment it is going to be as Chief Justice Roberts presides over the entire trial where 100 senators will sit silently in their seats, separated from their mobile phones which must be checked in beforehand.

In marked contrast to the usual lengthy speeches delivered by senators to a nearly empty chamber, no talking or debate is allowed in the chamber during the trial. Under Senate rules, senators serving as jurors are supposed to listen, not publicly debate the trial’s rules or even Trump’s guilt or innocence.

While something of a television spectacle will ensue as arguments between House prosecutors and the president’s lawyers are broadcast, the senators’ discussions on the most sensitive aspects of the trial will be in closed session.

As Andrew Prokop, the White House correspondent for the news website Vox observed a few days ago, the Senate is no ordinary jury.

“They get to make important decisions about how the trial should be organised and unfold. Rather than being selected for their lack of previous knowledge of the case, they are 100 political animals with pre-existing political beliefs, ambitions, and loyalties,” Prokop reminded.

Ultimately, the biggest question surrounding the trial will be whether the House’s allegations will get any serious consideration from the chamber’s Republican majority given that at the trial’s conclusion, it’s all but certain that majority will acquit the president and keep him in office.

Many close watchers of the US political scene say that for the past three years, the Senate has been one of the main arenas in which it has become clear just how totally and completely Trump has taken over the Republican Party.

Hardly surprising, then, that a number of senior Senate Republicans have repeatedly said they only see one conclusion to the trial.

“There is only one outcome that is suited to the paucity of evidence, the failed inquiry, the slapdash case,” said Senate majority leader Mitch McConnell last month.

On Wednesday, Politico magazine was cited by the New York Times as having counted 26 Republican senators who had already put out statements or otherwise publicly indicated that they would vote against Trump’s conviction and 24 more who probably would. Democrats, meanwhile, are said to be equally united around planned votes to convict.

“The suspense surrounding the trial, then, is not about the possibility that Republicans might suddenly change their minds about Donald Trump and his misdeeds,” says New Yorker columnist Susan B Glasser.

“The real uncertainty remains what it has been since the day Pelosi and the House embarked upon this impeachment course, last September: it is an uncertainty about what comes after the trial – after Democrats have taken their shot at Trump and, in all likelihood, failed,” insists Glasser.

In other words, for Trump to be removed from office there would have to be some truly shocking revelations or developments and only once the trial is under way will we know if such damning evidence can be brought to bear.

Then again this is Trump’s world and who knows what might come out of the woodwork?

If one thing is certain it’s that the already highly-charged partisanship of the American political landscape will find itself with another jolt as the trial plays out against a presidential election campaign now entering a crucial phase.

For weeks now Trump and his campaign team have been vitriolic about the impeachment process while simultaneously harnessing it to raise a lot of money and energise the president’s base. Now that the trial is about to really capture the headlines Trump’s approach will no doubt shift as he tries to draw a line under the damage it might still cause.

One White House insider is said to have described Trump as “livid” over the indignity of being impeached while fears remain that witnesses could yet make appearances at the trial, bringing with them unpleasant surprises. Even in the month or so since Trump was impeached more evidence has emerged about the Ukraine scandal.

And while many Republican senators argue that they shouldn’t hear new information, this only aids the Democrats, case that the Senate will end up covering Trump’s alleged misdeeds. To that extent it could be said that the Senate as much as Trump is on trial this week.

If, indeed, the announcement this Thursday on the “Doomsday Clock” confirms that the world is a more dangerous place, then it’s probably fair to say Donald Trump has played a hand in that escalation.

But as his impeachment trial will likely attest, those within his Republican ranks display few signs of wanting him out of office and Trump could still win another term. Should that happen, then who knows where the minute hand on the “Doomsday Clock” might sit this time next year.