There are multiple reasons why the current economic crisis is so toxic, but one additional, ­aggravating factor is that it is unfolding five weeks away from a US election. The disruptive effect of that was clear on Monday, when the US House of Representatives voted down President Bush's bail-out plan — a function of both his dead-duck status and the fears of 228 Congressman seeking re-election next month. The result is that the stakes in the contest between Barack Obama and John McCain, already stratospheric, have just got higher. The winner will be charged with leading the world through this economic ­convulsion and steering us all to safety. The current polls have Obama in front, but this contest could go either way.

Those of us on the outside will ­follow every twist; it is a statement of the ­obvious that the entire world will be watching on November 4. But perhaps we shouldn't be. At least if my email inbox is anything to go by, we should have only the scantest interest in the ongoing US election. After all, it's got nothing to do with us.

Or, as one emailer put it: "We are electing the President of the United States and the world can choke on it." His was one of a deluge of mainly hostile responses to a column that appeared here three weeks ago, arguing that the world's verdict would be harsh if Americans chose McCain over Obama. In their thousands, Americans wrote to tell me they read my words not as a simple prediction of the consequences of an American decision broadly to maintain the Bush-Cheney approach — but as some kind of threat. I was not merely commenting on the US election, they said, but intervening in it, seeking to blackmail American voters with the threat of global ostracism (as if I'm in a position to issue such a threat).

The counterblasts featured all the usual themes familiar to any columnist or blogger who wades into this terrain. America had saved Europe's "ass" twice before — and we would doubtless come bleating for help again when we inevitably sought rescue from the Muslim hordes imposing sharia law on London, Paris and Berlin. We can't defend ourselves, of course, because we are limp-wristed "Euroweenies", effeminate socialists whose own decline robs us of the right to say anything about the United States, which remains the greatest nation on earth.

Britain specifically forfeited the right to meddle in US affairs more than two centuries ago, when it lost the War of Independence. Besides, Obama is a Marxist, so Europe is welcome to him. One Bill07407 managed to capture the flavour of this virtual avalanche — including the curiously homoerotic undercurrent that runs through much rightwing American invective — with this effort: "If you want Comrade Obama we will gladly ship him over after he loses in a landslide. Meanwhile you can kiss my ass. I bet you would enjoy it faggot." Equally reflective, this from bioguy777: "I love it! A pansy-ass limey Brit begs the US to do his bidding while his own country slips further towards total Islamic rule. We're electing McCain, and the rest of the world can piss up a rope if they don't like it. 1776, BITCH!"

In among the abuse were three ­arguments that need addressing. The first is that this election has nothing to do with those of us outside America (so "butt out"). The trouble is, it has plenty to do with us. That has been true of every contest since 1945, when the US emerged as the sole superpower in the democratic world. But it has been undeniable since 2001.

Take Britain. Our soldiers have fought in two wars, Afghanistan and Iraq, that were wholly conceived and planned in Washington. Sure, it was Tony Blair's choice to take part in the invasion of Iraq, but that meant following a decision that had been made by an American president. No one doubts that had George W Bush decided the other way, Britain would not have gone to war in 2003.

If not blood, then treasure. The financial crisis now devouring British banks bears a three-word stamp: "Made in America." It was the US fad for sub-prime loans, handing out money to would-be homeowners who were not creditworthy, that triggered the credit crunch and, with it, the current turmoil. Yesterday President Bush acknowledged that its impact would be felt outside US borders when he sought to "assure our citizens and citizens around the world". Never was the hoary cliche truer: they sneeze and we catch a cold.

If war and economic meltdown aren't sufficiently persuasive, then how about a planetary emergency? The US is a first-rank contributor to the problem of climate change, responsible for a quarter of the world's greenhouse gas emissions, despite having just 5% of the world's population. But, as ­Thomas Friedman argues in his new book, Hot, Flat, and Crowded, the US is also indispensable to any solution. Only a radical transformation of America's approach to energy — generating it more cleanly and using less of it — could establish the kind of model and foster the technological innovation that would set a lead followed around the world.

So, Americans who say that since they don't poke their nose into our domestic affairs we should stay out of theirs, are making a bogus comparison. The battle of Brown v Cameron won't affect them. But the battle of Obama v McCain will affect me and every other Briton, ­European and citizen of the world. It could determine whether we are at peace or war, whether our ­economy thrives or enters a depression. This is not a mayoral election in rural Bulgaria, a purely internal matter of interest only to the locals. It damn well is our business.

What's more, Americans would not have it any other way. They like to define their president as the "leader of the free world". So why is it such a cheek if the free world shows some interest in who that leader will be? Americans, you can't have it both ways: either you're the global superpower, in which case the world has a stake in your future direction, or you're not. But you can't act like ­America and expect to be treated like Liechtenstein: it doesn't work that way.

The second charge to be defeated is that to talk like this is somehow anti-American. The ­reverse is true. For what is prompting non-Americans to follow the ­current election so closely is not just an acknowledgement that the US is the dominant force in international life, but a yearning for America to lead once more. I saw that clearly in the crowd of 200,000 that greeted Obama in Berlin in July. They wanted to feel about an American president the way their parents had felt about John F Kennedy, to be awed once more, as Bill Clinton puts it, by the power of America's example, not the example of its power. And, for most non-Americans, that means an end to unilateral wars and a moral lead on climate change — not a continuation of the past eight Republican years.

Lastly, those Americans who say they don't give a "rat's ass" what the rest of the world thinks are letting themselves and their country down. America was never meant to be a closed, introverted nation, turning its back on the world. It has always aimed to inspire the rest of us, to be a shining city on the hill. In these autumn weeks, the world is ­looking to the city once more, hoping desperately that the light is not about to fade.

freedland@theguardian.com