The rise of Donald Trump is saving Hillary Clinton from the American Jeremy Corbyn

Fortunately for her, you can have only one zany candidate at a time

Hillary Clinton peers over a podium while addressing an audience on the campaign trail in North Charleston. (Associated Press)

American politics is so unlike British politics that it is dangerous to draw parallels, but that won’t stop us. And it doesn’t stop them, as the publication of the latest batch of Hillary Clinton’s emails shows.

Among several emails discussing Labour’s problems, sent to Clinton by her adviser Sidney Blumenthal, is an article of mine, published on the evening of Ed Miliband’s election as Labour leader five years ago. I wouldn’t mention it except that it was one of those that hasn’t been mocked by later events. I said: “Even if Ed Miliband had won comfortably in all three sections of Labour’s electoral college, I feel he would still struggle against Cameron.”

Labour Party members and MPs were right, I said, to think that David Miliband, Clinton’s friend, was the better choice. As Blumenthal commented, Ed Miliband’s narrow victory was “the revenge of old Labour”. As it turned out, David Miliband’s disappointment was just the start of it. In one of his emails to Clinton he said: “Losing is tough. When you win the party members and MPs doubly so. (When it’s your brother...).” Now the revenge of old Labour has become many times worse, with Jeremy Corbyn’s likely installation next week.

The parallels with what is happening in American politics have become irresistible. Clinton, running as the inevitable candidate for the Democratic Party nomination, has come up against Bernie Sanders. Sanders is so left-wing that he doesn’t usually run as a Democrat. He describes himself as a socialist, which is pretty unusual in America, and was elected senator for Vermont as an independent. Like Corbyn, he is older – 74 next week, although Clinton herself is 67, a year older than Corbyn – and has no support in the party establishment.

Yet, like Corbyn, Sanders is confounding the commentators and pollsters. Three weeks ago, Harry Enten of FiveThirtyEight, the data-driven website created by Nate Silver, wrote: “The Bernie Sanders surge appears to be over.” On Monday he had to recant, admitting that Sanders was continuing to pick up support in New Hampshire and probably in Iowa too. The Sanders phenomenon is not as powerful as the Corbyn one, and, as long as the Labour leadership contest has seemed, the US nomination races are even longer still. Clinton is still seven points ahead in the latest poll in Iowa, where the caucuses, the first test of primaries season, are likely to be held on 1 February.

The echoes of Corbyn in Sanders are unmistakable, but the senator is different from Corbyn in that he has experience of running things. He was a mayor of Burlington, the largest town in Vermont, and chairman of the Senate Committee on Veterans’ Affairs. Yet he, like Corbyn, is admired for the consistency of his views, which are sharply distinguished from those of his mainstream opponents – of which there is only really one: Clinton. He opposed the Iraq war, he thinks Obama’s healthcare reform doesn’t go far enough, he wants to raise the minimum wage, cut student debt and tax financial transactions. He is drawing crowds – 10,000 in Wisconsin the other day – that fill rivals with envy and supporters with certainty.

Clinton, on the other hand, has recently served in government and before that she voted for the invasion of Iraq. Now she is wading through the treacle of the emails business, which I do not pretend to understand. Apparently, when she was Secretary of State, she used her personal email address to send and receive electronic messages. This is a terrible scandal because under Freedom of Information law it gives journalists a lot of documents, some of them written by me (have I mentioned?), and others of which are redacted. Anyway, for reasons too complicated to go into – Americans never got into our hoo-ha over Michael Gove’s emails either – Clinton is in trouble and Sanders is fiercely hailed as a break from politics as usual.

Then, however, the parallel duplicates and diverges, because America has not one but two Corbyn-a-likes. There are similarities not just between Corbyn and Sanders but between Corbyn and Donald Trump, who is currently rampaging through the Republicans’ china shop. My colleague Rupert Cornwell wrote in The Independent on Sunday about how dismissive he had been of Trump’s candidacy, but how he had to admit: “The more he ignores the accepted rules of politics, the more the voters love him.” Like Mr Enten on Sanders, and me on Corbyn, Cornwell accepts that he misjudged the wave of interest in a novelty candidate, but insists that it will all end badly anyway.

Which it will. For the moment, though, Trump carries all before him. Well, he has a 15-point lead in a jumbled field and he is currently tied with Ben Carson, the neurosurgeon, in Iowa. We are at that fascinating stage of an open-field primary, as wonks try to put the names to the candidates – Carson, Jeb Bush, Ted Cruz, Marco Rubio, Carly Fiorina – and assess their chances, when along comes a verifiable object of ridicule and turns the whole thing into a branch of the entertainment industry.

And Trump may well be the saving of Clinton’s campaign. Because you can have only one defy-the-rules, infuriate-the-establishment, zany candidate at a time, and Trump, the “perpetual attention machine” is bigger, crazier and more publicity-hungry than Sanders. Thus Clinton may get away, after all, with being an experienced political insider who knows how to make boring incremental change happen in large bureaucracies. She may be able to bear the terrible burden of being regarded as a sell-out by middle-class socialists because swing voters think she could take a 3am telephone call about national security.

There would be some kind of mirror-justice in David Miliband’s centre-left friend winning the nomination and then possibly the presidency while a species of Corbynmania lays waste to the Republican Party. Just as Corbynmania is a raging version of the homeopathic delusion that brought David’s brother to the Labour leadership, so the Trump-a-thon is an intensification of the Tea Party infection still coursing through GOP veins.

Then, on Monday, Kanye West announced he was running to be president (presumably for the Democratic nomination, as he attended a fundraiser for Clinton last month). But no one would take that seriously. Would they?