Nevermind the Oscars or the Baftas. There are few stages that look so white as a Democratic debate in Iowa in early 2020.

It wasn’t just the recent departures of every leading candidate of color in this contest to unseat our orange president.

Somehow the makeup caked on the faces of the surviving contenders made them look even more white than the frozen cornfields they watch through the windows of their campaign buses all day.

Until one moment, after an hour of earnest discussion about national security, when the blood suddenly rushed into Bernie Sanders’ cheeks.

On the face of it, Bernie’s face was burning from the much-anticipated discussion of a pre-election conversation with his former friend and current rival Elizabeth Warren. Did he really say a woman couldn’t win an election? Did she really fib about what he’d said behind closed doors?

For two candidates who like to talk about structural, radical change, this sounded like a good old-fashioned dispute about spilling beer in a crowded bar. The beverage was just an excuse for a beating.

Only Sanders got suckered into a different dispute – not about women, but about winning. Specifically, whether he could beat an incumbent Republican. And more specifically, whether he could add up.

“Look at the men on this stage,” Warren said. “Collectively, they have lost 10 elections. The only people on this stage who have won every single election that they’ve been in are the women. Amy and me. And the only person on this stage who has beaten an incumbent Republican anytime in the past 30 years is me.”

Until this point, Sanders had given a fine account of himself, denying any sexist sentiment, pledging his support for the ultimate nominee, and even praising Hillary Clinton for winning the popular vote. Which hasn’t exactly been his most popular talking point for the last three years.

But that wasn’t enough for Sanders, who decided to dispute Warren’s real attack: that none of them had beaten a Republican for 30 years. Sanders insisted he had, back in 1990, done just that.

Elizabeth Warren speaks with Bernie Sanders as billionaire activist Tom Steyer listens after the seventh Democratic 2020 presidential debate at Drake University in Des Moines.

Photograph: Shannon Stapleton/Reuters

Warren smiled and pretended to do the math. Sanders grew flustered as it dawned on everyone that he thought 1990 must be more recent than three long decades. His cheeks flushed brightly and he spluttered his way through an emphatically delivered diatribe about nothing in particular.

So much of Tuesday’s debate was a matter of time travel. In the contest to fire a 73-year-old president, a 78-year-old socialist senator spent the first half-hour of a TV debate arguing with a 77-year-old former vice-president about their respective decisions to vote on the war in Iraq 17 years ago.

There are voters preparing to caucus in Iowa who were not born when these old men were first arguing about weapons of mass destruction.

The ghosts of that time stalked the stage in Des Moines at the final debate before the fateful first votes in this election year.

The last time Democratic voters picked a nominee to run against a gun-slinging Republican president, they faced a stark choice between a leftist populist and a centrist snoozebag. After dating Howard Dean, they married John Kerry. Almost two decades later, the Democratic voters of Iowa face a similar choice between the rabble-rousers and the comfy pair of slippers.

Just three weeks from the first votes of the 2020 cycle, the final debate revolved around four candidates vying for two slots: Elizabeth Warren versus Bernie Sanders, and Pete Buttigieg versus Joe Biden.

It’s good manners to point out that there were two other candidates on stage: an entirely respectable senator, Amy Klobuchar, and an entirely forgettable rich white guy, Tom Steyer. Klobuchar had some fine moments urging the lefties to face up to reality. Steyer weirded out the nation by turning dramatically to look into the camera every time he piped up.

But with so little time left for Iowa to enjoy its brief moment of global importance, let’s not waste this blip in the historical record. For the Iowa polls suggest we’re looking at a four-way race, bunched up in the high teens or early 20s, depending on how many new voters the pollsters think will show up to caucus.

For most of the night, the steady establishment hands were only too happy to look down on the chaos and lament the lack of credibility at a time when Tehran looks more restrained than Trump. They didn’t even bother to point out when Sanders confused George W Bush and Donald Trump when he was talking about support for the Saudi bombing campaign in Yemen.

Back in the 2004 campaign, it was the capture of Saddam Hussein in December 2003 that marked the moment when Dean began his collapse and Kerry rose up from the depths of his dismal polling to take the nomination.

Judging from this final pre-Iowa debate, it sorely needs the defibrillator that Donald Trump represents

Back then, Joe Biden was a surrogate for Kerry, testifying to his friend’s national security experience and leadership skills. Today, Biden’s strongest moments on stage were when he was silent. His defense for his vote on the war in Iraq was that Barack Obama hired him. His best argument for the boldness of his healthcare plan was that Obamacare was a big effing deal.

It is still true that the idea of Joe Biden is rather more impressive than the reality. And much of that notional Biden is built around his old friend Barack.

This is a big moment for the tiny state of Iowa (population: 3.2 million), so the final Iowa debate was held in a room that appeared no bigger than your average display of butter sculpture. As the candidates scribbled their pre-debate notes in the minutes before the debate began, CNN’s pundits were close enough to the stage that they hushed themselves for fear of disturbing the candidate’s brainwaves.

But in just a few weeks, Iowans will do something very big: award winning tickets to no more than two of the Democrats on stage this week.

In the meantime, they and the rest of the nation will be consumed by the impeachment of a very stable genius.

Even more than an Elizabeth Warren debate trap, the trial will bring a rush of blood to this contest. Judging from this final pre-Iowa debate, it sorely needs the defibrillator that Donald Trump represents. Democrats are looking for a candidate to beat Trump even more than a candidate with the best plans for healthcare reform.

As the impeachment trial sinks into an Iraq-style quagmire, Iowa’s Democrats may start to look at this race anew. The winner may well be the candidate who knows how to turn that moment of Trumpian triumph into a rallying cry for disappointed Democrats.