Joe Biden, Barack Obama's vice-president for two terms, earlier served as a senator from Delaware from 1973 to 2009.

The length of Biden's service as a senator, which began almost as soon as he was constitutionally able to be one, is the source of many a piquant observation.

One striking fact that can be teased out is that during his 36 years as a senator, Biden at one time or another served alongside no less than seven other senators who had been or, like him, would go on to become the presidential candidate of the Democratic Party.

Only one of these seven senators - Barack Obama - actually made it to the White House. The list of unsuccessful Democratic nominees who sat in the Senate with Biden is long indeed.

Let their names be tolled: Hubert Humphrey, George McGovern, Walter Mondale, Al Gore, John Kerry and Hillary Rodham Clinton.

They all lost - and to be a loser in America is a sad fate.

Their combined unsuccess led to almost a quarter-century's exclusion for their party from the inner sanctum of US democracy.

But their collective aura is suddenly now less dispiriting.

Joe Biden's imminent accession has had the effect of lessening the air of failure surrounding these six of his former senatorial colleagues. His success required him to overcome deep problems which led to their individual undoing.

Things began in 1968 when Hubert Humphrey, a senatorial colleague of Biden's from 1973 to 1976, lost to Richard Nixon.

Biden is a centrist, as Hubert Humphrey was in his own way. At the start of his career in the McCarthyite era, Humphrey was demonised as a crypto-communist. His liberalism offended racists, initially in the former Confederate states and then elsewhere. Then during the Vietnam War era, it was rabid anti-war protestors who demonised him. Their violent demonstrations alienated mainstream opinion.

Humphrey was fatally beset on both flanks in a two-front war, but Biden avoided such a fate in 2020. He was a moderate and a Washington insider, and yet he oversaw a campaign which marched to victory without alienating energetic left-wing elements in his party led by Bernie Sanders.

Senator George McGovern, who ran against President Richard Nixon in 1972, was no centrist - and paid the price. He lost in a landslide.

Nixon wanted to pulverise the Democrats.

His resort to dirty tricks - which culminated in the Watergate scandal - paid off in the short-term, as did appeals to racism by his running mate Spiro Agnew.

Within two years, however, both Nixon and Agnew were revealed to have committed sackable offences and were forced from office.

The American constitutional system is designed to root out or frustrate malignant or corrupt elected officials, as Biden's success in 2020 election has reaffirmed.

The third of Biden's senatorial colleagues who went down to defeat was Walter Mondale.

President Ronald Reagan defeated Mondale in a landslide in 1984. Reagan's electoral triumph was an endorsement of the neoliberal policies that flourished during his presidency.

Over the following decades, the cult of deregulation and lower taxes has had the effect of hollowing out public and civic safeguards and standards, culminating in the absurdities and worrying behaviour of the Trump administration.

Trump switched parties for the first of several times when he became a Republican under Reagan. His defeat in 2020 marks a welcome attempt to wind back some the long-term effects of Reagan's 1984 evisceration of Mondale.

In the 2000 US election, the defeat of vice-president and former senator Al Gore was sealed by a Supreme Court decision on the electoral result in Florida.

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The court, by a single-vote majority, ruled in favour of George W. Bush. Trump hoped to emulate this process at the end of 2020, but did not succeed. The threat of substantive judicial intervention in the electoral process seems to have been knocked back. The memory of what happened to Gore made the Democrats all the more vigilant under Biden. The chastening experience in 2000 was not repeated.

In 2004 the power of incumbency was powerfully reaffirmed when Biden's senatorial colleague John Kerry failed to prevent President George W. Bush's re-election.

But Biden, unlike Kerry, has unseated an incumbent. His having done so weakens the aura of incumbency which is ever a salutary thing.

In 2016 Hillary Rodham Clinton ran against Donald Trump. In November of that year rationality and enlightenment lost out to demagoguery. After eight years of Barack Obama - one of the more cerebral US presidents - voters opted for something cheaper and nastier.

Pro-Trump elements were energised when Clinton seemed to dismiss them as "deplorables". They chaffed against the rules and norms developed by scientific experts and enlightened bureaucrats.

The 2016 election's embrace of unreason and impulse came unstuck with a vengeance three years later when a global pandemic afflicted the United States.

The gulf between the White House and professionalism and expertise during the pandemic has had disastrous consequences.

It is the destiny and duty of the incoming president to end this destructive rift.

In ending the Trump presidency, Joe Biden has done his nation a great service.

His victory has also had the effect of repairing, in varying degrees, the reputation and standing of the six fellow Senate Democrats who ran for President but who, unlike him, fell short.

They come across as looking less like a bunch of losers now.