If, as seems likely, at least some of the trials take place in the run-up to the election, Trump will aim to turn the courthouses into the equivalent of stadium rallies: arenas in which to commune with his base. The presidential race would become a courtroom drama, a historical passion play where he can portray himself as a MAGA martyr. “In the end, they are not coming for me,” he told a rally last June, “they’re coming after you - and I’m just standing in their way.” It is a typically brilliant Trumpian formulation, which taps into the persecution complex he shares with supporters. Trump is seeking to override a fact-based criminal justice system with a feelings-based political process.

The prosecution of Trump will help him win the Republican presidential nomination. But polls suggest that guilty verdicts would damage his chances of regaining the presidency, although, constitutionally, that would not automatically disqualify him either from running or taking office.

In assessing his electability, naturally we tend to focus on his cult-like MAGA followers, his sycophantic enablers on Capitol Hill and the near 70 per cent of Republicans who believe – without any factual basis – that Biden somehow “stole” the 2020 election. However, it is the 30 per cent of Republicans who have not bought into Trump’s big lie who could decide the contest. They formed part of the sensible majority that asserted itself at the congressional midterm elections in 2022, when Trump-backed election deniers underperformed, as did the Republican Party as a whole. Suburban women, especially, have rejected Trump’s craziness and ugliness, and they make up a crucial swing demographic that regularly decides presidential elections.

Yet much has happened in the 18 months since those midterm elections. Now aged 81, Biden is a year-and-a-half older for a start. He also has the worst approval rating of any president seeking re-election at this point in the electoral cycle.

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Nor is January 6 so fresh in the minds of voters. “As a Biden campaign theme, I think the threat to democracy pitch is a bust,” the Republican Senator and Trump critic Mitt Romney told the New York Times. “Biden needs fresh material, a new attack, rather than kicking a dead political horse.”

The Biden campaign, not to mention prosecutors in the January 6-related cases against Trump, will hope to remind voters of that day’s myriad horrors – although proceedings in the federal trials will not be televised, which could reduce their impact.

Besides, for some Democratic voters January 6 is now of less consequence than October 7. To many Muslim voters, 83 per cent of whom voted Democratic in 2020, Biden’s support for Israel’s brutal response is more galvanising than Trump’s Islamophobia. The Gaza war has become an overriding issue. And while they will not necessarily end up voting for a former president who vowed repeatedly to ban Muslims from entering the United States, the problem for Biden is that they might boycott the election.

Within the multi-ethnic and multi-generational coalition that secured Biden victory four years ago, there are further signs of fraying. Trump has been polling unexpectedly well among young voters, as well as black men and Latinos.

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In 2024, moreover, disaffected voters have more options. Robert Kennedy Jr. is a fringe candidate, but one born with that most valuable of political assets: instant name recognition. The African-American academic Cornel West, who is also running, could tap campus discontent. The Greens candidate Jill Stein – who did well enough in 2016 to deprive Hillary Clinton of victory in the vital battleground states of Pennsylvania, Wisconsin and Michigan – is running again.

Though under attack on multiple fronts, Biden should win the nationwide popular vote, as Democratic candidates have done in seven of the last eight presidential elections. However, given the flaws of the Electoral College, which was designed by founding fathers who feared what they called an excess of democracy, that will not be enough – as Al Gore and Hillary Clinton can attest.

I still want to believe that America harbours a sensible majority alert to the risks that Trump poses to democracy. But an overriding question in 2024 is whether those voters will outnumber Trump supporters in the six key battleground states where America’s future will be determined.

Nick Bryant, a former BBC Washington correspondent, is the author of When America Stopped Being Great: A History of the Present.

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