Bernie Sanders holds the result of the US presidential election in his hands. You wouldn’t have believed that three months ago – just as you wouldn’t have believed Donald Trump would be the Republican nominee; or that Trump would have wrapped up the nomination before Hillary Clinton, the same Hillary Clinton whose victory, everyone thought, would be an instant Democratic coronation.

And who could have imagined that if there’s to be a chaotic convention in 2016, it’s now far more likely to happen when the Democrats assemble in Philadelphia in late July, rather than when Trump completes his hostile takeover of the Republican party, a week earlier in Cleveland. But a lot of very worried Democrats who support Hillary Clinton are imagining precisely that. And all because of a cantankerous 74-year old proclaimed socialist who, formally, is not considered a Democrat at all.

Now no-one would deny Bernie Sanders’ positive impact on campaign 2016. He’s raised questions that desperately need asking: should the US have a single payer health system, should Wall Street be placed under tighter control, is the US political system a sham, controlled by big money and the highest bidder? Just as Trump with Republicans, he’s brought legions of new Democratic voters, especially younger voters, into the political process.

Bernie Sanders draws thousands to rally in New Jersey

The fact is however that he has lost, despite a recent string of primary and caucus victories. In the 43 state contests held so far, Clinton has won 3 million more votes. To overtake her in pledged delegates, Sanders must pull off colossal victories in the two important primaries that remain, California and New Jersey. It isn't going to happen. And that’s not to mention the superdelegates, roughly a seventh of the total in Philadelphia, who overwhelmingly support Clinton.

But Sanders won’t concede defeat and allow the party to close ranks for the general election battle against Trump. There’s nothing wrong with that per se. In 2008, Hillary soldiered on against Barack Obama until June. But, given that he’s much further behind than she was at a similar stage eight years ago, Sanders might at least be expected to tone down the rhetoric, so that the liberal insurgents and the party establishment can more quickly make peace.

People who will flee America if Donald Trump wins Show all 8 1 /8 People who will flee America if Donald Trump wins People who will flee America if Donald Trump wins Miley Cyrus 'God’ he thinks he is the f***ing chosen one or some shit! … Honestly f*** this sh*t I am moving if this is my president! I don’t say things I don’t mean!' Jemal Countess/Getty Images People who will flee America if Donald Trump wins Whoopi Goldberg 'I don’t think that’s America. I don’t want it to be America. Maybe it’s time for me to move you know' People who will flee America if Donald Trump wins Samuel L. Jackson 'If that mother**er becomes president, I’m moving my black ass to South Africa' People who will flee America if Donald Trump wins Raven Symone 'My confession for this election is, if any Republican gets nominated, I’m gonna move to Canada with my entire family. Is that bad? I already have my ticket. I literally bought my ticket, I swear' People who will flee America if Donald Trump wins Cher 'If he were to be elected, I'm moving to Jupiter' People who will flee America if Donald Trump wins Neve Campbell 'I’m terrified. It’s really scary. My biggest fear is that Trump will triumph. I cannot believe that he is still in the game ... [I'll] move back to Canada' People who will flee America if Donald Trump wins Jon Stewart 'I would consider getting in a rocket and going to another planet, because clearly this planet’s gone bonkers' People who will flee America if Donald Trump wins Randy Blythe 'He could just be a clown. If he is the president, though, I am leaving America 'till he's gone'

Not a bit of it, however. His language against Clinton, and even more the Democratic National Committee is growing fiercer. The DNC has rigged the system, Sanders claims, while she is the creature of a rotten status quo. His most passionate followers even urge him to run as a third party candidate if he loses, which would hand the election to Trump. As Democrats found out with Ralph Nader and the Green Party in 2000, uncompromising idealists can be even more dangerous than incompetent rascals.

Until this week, Hillary has mostly turned the other cheek. But on Thursday her frustration boiled over. Her lead, Clinton pointed out, was insurmountable. Just as Sanders now, she had reeled off a string of late primary wins in 2008 that didn’t matter. The message was clear. Yes, defeat is really tough after such a long campaign – I’ve been there and I know. But for the good of the party, get over it.

Odds are they will still make up. Both agree the enemy that matters is Trump. Eight years ago, even more Clinton supporters vowed they would never vote for Obama than the Sanders followers now who say they will not vote for her in November. But that fury quickly subsided. And already the Clinton camp is offering Sanders greater representation on key convention committees.

Almost certainly, he’ll be granted a big say in the official party platform (platforms, incidentally, count for little in US presidential elections – certainly far less than party manifestos in British general elections). Organisers surely believe it's better to have an agreed platform that may be to the left of what Clinton would prefer, than a public brawl over the platform on the convention floor.

But after the fracas at last weekend’s convention in Nevada, to apportion the state’s delegates for Philadelphia, you have to wonder. The disputed procedural points are too arcane to go into here. What mattered was the physical near-fight that ensued. So menacing were the Sanderites protests that the whole event had been rigged, that police had to clear the premises. One US Senator present, the Clinton-supporting Barbara Boxer of California, said afterwards she had been scared for her own safety.

Pressed by party elders to disavow what happened, Sanders issued a mealy-mouthed condemnation, but spent more time accusing Nevada’s Democrats of preventing “a fair and transparent process", which is a bit rich, given that until he declared his candidacy last year, Sanders wasn’t even a Democrat at all.

More understandable is his argument that polls show him beating Donald Trump by an even larger margin than Clinton. But people vote for the candidate they want, not the one they logically should want. By that token, Republicans ought to be clamouring for John Kasich, their primary candidate who polled best against the former First Lady, to be the party’s standardbearer in November. But they’re not.

Should Sanders persist in his obduracy, he will provoke a showdown in Philadelphia live on national TV. Conventions in this age are designed as four-day party infomercials. A divisive or shambolic one virtually guarantees defeat in the general election – as in Chicago 1968, or the chaos in Miami four years later, which saw nominee George McGovern give his acceptance speech at three in the morning.