Only touch the hem of Barack Obama’s garment and believe. The new Messiah is flying out to Europe and the Middle East this week, concluding his visit in Britain. Our sinful politicians will hope to be healed by his charisma and a good photo-opportunity. For Gordon Brown the balm may be in short supply. David Cameron would like to bottle it.

There will be nothing quite like it for sheer spectacle. An American media circus will perform like an adoring choir of angels. The television crews accompanying the senator from Illinois on his plane will be steeped in a ritual prescribed long ago in Theodore White’s The Making of the President, about John Kennedy’s epic campaign against Richard Nixon in 1960. They, too, want to be present at the creation of a new national myth.

Obama’s team reprise the cult of the great Democratic martyrs, JFK and his brother Robert. The highlight of the tour will be a grand performance in Berlin where Obama-mania has reached dizzying heights. Here Kennedy in 1963 enthralled huge crowds with his declaration that “Ich bin ein Berliner.” Twenty-five years later it was a Republican hero, Ronald Reagan, who trumpeted that as in biblical Jericho, so in divided Germany, the Wall must come tumbling down.

Unfortunately for Obama, his German hosts don’t want to seem too partial to his candidacy and denied him the Brandenburg gate. The setting for his speech is likely to be an airport that kept the city fed during the Soviet land blockade of 1948-9. The rhetoric will still be powerful. As Jon Stew-art, the pithy American satirist, says of Obama’s quest: “So far, our take is that he is positioning himself to be on a coin.”

The senator’s neo-conservative critics don’t find him funny at all. Charles Krauthammer, the influential columnist, takes aim at the royal “we” in Obama’s slogan, “We are the ones we have been waiting for”, his narcissism and “the gaps between his estimation of himself and his actual achievements”. Having been in a live audience for Obama’s rolling cadences, I can understand Krauthammer’s frustration but feel he misses the point.

There is a kinship here with the youthful Tony Blair – he of the verbless sentences – who also mouthed platitudes in quasi-religious language. A high moral tone may set the teeth of the worldly wise on edge, but it appeals to an audience that yearns for inspiration, not shop-soiled poli-ticking. Obama offers redemption from America’s original sin, racial inequality.

Blair, the practising Christian, also stage-managed his own myth. Remember the timing of his entrance to his first election victory celebrations on the South Bank in London as the sun rose. “A new dawn has broken, has it not?” he preened. You may think this strategy too closely echoes George W Bush’s naughty quip, “You can fool some of the people all the time and those are the ones you want to concentrate on.” But it works.

In London our insular political class is tarnished by sleaze and appears deeply distant from the electorate. Obama famously connects: he addresses huge enthusiastic crowds in vast sports stadiums, packed out with young people normally alienated from the process. An opinion poll conducted here shows he is overwhelmingly Britain’s choice to be the next US president.

Brown will look forward to his visit with anticipation tinged with regret. He would have enjoyed teaming up with Hillary Clinton, the failed Democratic candidate with whom he is already familiar – the two control freaks and wonks have much to share, even resentment at being overshadowed by their political partners Bill Clinton and Tony Blair.

The Republican candidate Senator John McCain, if elected, will be 72 years old: his presence will hardly diminish our prime minister. But Obama’s dazzling light will surely cast Brown into obscurity on any shared international stage. The fact is, Brown has thrown away his own moral compass. And with it went his strongest claim to rule. Britain may not have loved this son of the manse, but he had earned our grudging respect. His economic policy was couched in the language of moral disapproval of Tory boom and bust. He brought a puritanical uprightness to the management of our finances. Now the revision of the Treasury’s fiscal rules shows that all along he was spending like a drunken sailor on shore leave. No more sermonising, please.

Nevertheless, Brown will try hard to engage with the younger man. He will greet victory by the Illinois senator in November as proof that the new Demo-crat/new Labour progressive middle is still alive and kicking. When Bill Clinton left the White House, the new Democrats looked intellectually moribund. John Kerry, their last presidential candidate, had a charisma bypass too.

Most Blairites have always believed that Brown could not connect; but now the prime minister, like Bush, has become a leader defined by his unpopularity. In Blairite eyes, the popularity of the Obama campaign proves what happens when you change a tired, discredited leader for a shiny new one. I note that the clever former Blairite James Purnell, the work and pensions secretary – studiously loyal to the prime minister – predicted to me months ago that Obama would win because of his message of hope. There’s little of that on Labour’s back benches.

Cameron’s take on Obama is intriguing. When the Conservative leader appeared friendless abroad, it was McCain who came to the rescue by delivering a speech at his Bournemouth party conference. In theory, Tory and Republican are ideological soul mates. Yet there is an obvious affinity between the two young men, the voice of a new generation, running against older political insiders and with a background of economic despair.

Change is indeed abroad. First Blair, then Bush and John Howard of Australia stumbled. The French voted for Nicolas Sarkozy’s Rupture even if all they got was Carla. “The appetite for change is not satisfied,” says a hungry top Tory.

Obama makes appeals to his countrymen as individuals to rise above race, political creed and geography “in a new consensus”. The British opposition leader decries the big state in moral terms. As one intellectual shadow minister puts it: “We are tailoring our solutions to the individual. Brown’s measures are materialistic, quantitative, often financial . . . we are looking for a more human engagement than with desiccated statistics.”

The sentiment is echoed by an elite group of Republicans who support the Democratic nominee for president, the so-called Obama-cons. Larry Hunter, who worked in the Reagan White House, wrote last week in the New York Daily News of his dismay that Bush has presided over a huge rise in government spending and costly foreign interventions. McCain represents no change, he says. “I believe he [Obama] is savvy enough to real-ise that the real threat to middle-class families and the poor – an economic undertow that drags everyone down – cannot be counteracted by an activist government.” Not so much Obama’s proclamation of “the Audacity of Hope” as the Audacity of Despair then.

Obama, the left-libertarian who takes his ideas from everywhere and appeals to the centre-right, is matched by the Cameron who wants to steal the mantle of the centre-left.

There is a small serpent in the Tory leader’s paradise. Cameron would like to be as popular as Blair was before 1997 and as Obama is manifestly now. But his lead in the polls derives from distaste for a decade of Labour rule and Brown’s annus horribi-lis in No 10, not love of the opposition.

If an election were held tomorrow it would be a Tory triumph. But are the huge polling leads sustainable? The sheer speed of Obama’s rise is a key asset. How tired and tarnished Hillary Clinton looked as the primary campaign progressed. Cameron must fear that another two years around the block will grind the Tories down and leave the public jaded.

Obama appeals to black fathers to take up their responsibilities. Cameron echoes him and further demands that we all pull together to rescue the broken society. Tories with long memories of John Major’s back-to-basics speech, which foundered on his party’s sleaze, sharply hold their breath. As Major and Brown found out, it is a dizzy drop from the moral heights.

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