In New York post-election goodwill lingers like birthday balloons that no one can bear to take down. In the groovy T-shirt shop on 8th Street, Obama merchandise - Barack is My Homeboy, Hope Won etc - now outsells the evergreen I NY. The city has rushed to Joe Turner's Come and Gone, a Broadway show that the First Couple saw last week (though it is long, ponderous and achingly right-on) and snapped up copies of that cardie in which Mrs O cuddled the Queen.

It was most calming to browse news stands not dripping with scorn and fury, to flick through the frocks in the adoring glossy mag Michelle: 100 days of style. Where was the Heat magazine “ring of shame” pointing out a sweat stain or some odd-shaped big toe? Even the many tax dollars spent on the aircraft convoy for the presidential date night received less opprobrium than Gordon could expect for buying Sarah a lager top in Wetherspoons. “The prez gets to do normal-people stuff too,” gushed the Daily News.

Meanwhile, my fellow Brits and I pored over faraway rumours and resignations. Smith, Blears... “Wow, it's getting scary!” cried a colleague. Indeed it was deeply unsettling to board a night flight from JFK not knowing who would be prime minister by the time you taxied into Heathrow. Only in a parallel political universe, where a nation is mighty pleased with its own electoral wisdom, do you realise the damage that the constitutional crisis is doing to our own national psyche.

For eight years we could, in equal measure, mock and pity America: for its culture wars, its nut-job religiosity and redneck unreason. We could sympathise with liberal friends about their word-fumbling comedy president, his sulphurous VP, torture, rendition, provincialism, paranoia... Not any more. Watching a dazzling Obama address the Muslim world you suddenly remember the point of America: its big-picture optimism and modernity, its epic generosity and can-do attitude. And Britain seems by contrast self-loathing, curdled, introspective, hopeless and small.

America - at last - has its real-life Jed Bartlett: we're stuck with a bunch of Alan B'stards. Now we have a PM bothering himself with failed candidates on Britain's Got Talent; they have a President who makes scholarly jokes, quipping that his classically trained spin doctor Rahm Emanuel “was the first to choreograph a ballet version of Machiavelli's The Prince”. A leader who can both wield the Koran and has a butt which, running up the steps of Air Force One, looks hot in white jeans. A President who has not only watched The Wire but is unafraid to say his fave character is Omar, a gay stick-up artist.

Why didn't Gordon Brown get out more, take his forbearing wife to the theatre, attend just one event that wasn't based on horse-trading or appearances? It would have lightened him up, given him oxygen and perspective, won a little public love. Instead he retreated to his gloomy bunker, surrounded himself with unworthy hatchet men and acolytes, anoints Lord Sugar of Amstrad, concentrates ever more on the internal and recondite.

Meanwhile, Mr Obama walks boldly into the heart of Islam, doesn't balk at raising women's rights and, more than that, demonstrates them by having Hillary Clinton beside him in a mosque. Imagine, a man with the cojones, the diplomacy and grace to award that great office of state to his fiercest former foe.

Great to see also that while Mr Obama left Egypt to make common cause with Angela Merkel over the economic crisis and nuclear disputes with Iran, that aspiring international statesman David Cameron has decreed that Tories in the EU will work not with her, but with a far-right posse of Gypsy-haters and homophobes, a sort of Borat Alliance.

And while Mr Brown gurns on YouTube, President Obama is blessed with a quality possessed by the most beloved movie stars: the ability to exude beatific happiness. Wandering smart-casually around the Sphinx or heading for dinner with his hand on his wife's elegant back, meeting the Saudi king or striding up to the lectern to convince a billion doubters, he looks equally at ease in his own skin.

And that happiness - or the appearance of it - is deeply attractive and a little contagious. Is it why New York, for all its tumbling real estate prices and unoccupied hotel rooms, maintains an upbeat vibe? Leadership during a recession requires strategy but can't disregard morale: like the best episodes of The West Wing, Mr Obama has a thrusting main plotline with some lighter tropes as well. Stevie Wonder playing the White House, the enduring and lovely marital romance, that naughty Obama pooch. America, for all its ailments, is enjoying this President.

Everyone I met in New York seemed to nurture a personal hope: a gay friend is thrilled that Mr Obama invited a same-sex couple to the White House egg-rolling, that Mr Obama has promised the end of the US military's “don't ask, don't tell”. A black cab driver cites Mr Obama's election as the reason his previously ne'er-do-well son returned to school. A businessman on the plane explains that he didn't vote for him, disapproves of his fiscal package, but adds warmly: “He's a stand-up guy - he wants the same thing I do, he's just going about it a different way.”

America moves on: Britain hangs in stasis. A nation's politics filters down, cascades from Hansard into the cerebral cortex. And I wonder how much of our broken, defeated Government, a system in which everyone has, temporarily or not, lost faith, this awful seeping nihilism is starting to infiltrate our lives. It must have been strange to be a first-time voter this Thursday when the major parties sat on the ballot paper with the BNP, UKIP or random celebs as seemingly equally valid options.

The expenses saga is depressing, but it is toxic, too, this ugly hounding, this insistence that they are “all the same”. And what does it say about our humanity that when Nadine Dorries warns that some MPs may be on the point of suicide, Mr Cameron must rebuke her for the crime of trying to make us care? Our public discourse, how we speak of our politicans or anyone prominent in national life, has grown dangerously poisonous and debased.

Only as I sat in my New York hotel room, watching Mr Obama, that embodiment of what democracy can bring forth, did I realise that I'd forgotten to vote in the British elections. And for the first time in my life, I didn't care.

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