Matthew Norman: Has anyone got the guts to challenge Gordon?

It is the nightly wet dream of Tony, and above all Cherie, that Mr Miliband be press-ganged into standing

In the golden age of risk aversion, you begin to wonder whether a monster Health and Safety executive is patrolling the giant playground known in some circles as the Muthah of Parliaments, doing to Gordon Brown's potential leadership rivals what his colleagues do to schookids.

Every name touted as a challenger has shrunk away, as if warned that playing conkers is too dangerous because Gordon might take your eye out, thereby equalising the ocular score at 1-1. As for a snowball fight, you can forget that because the Chancellor's just the kind of boy who'd pack his around a small but lethal rock.

It's true that John Reid appears to relish a battle, but he's too bald, aggressive, beset with failure and plain nasty, whereas Charles Clarke likes a scrap too much (to think of the money his parents spent on that finishing school in Geneva) to explain his monumental irrelevance. But the rest seem plain petrified of the old bruiser, seeking refuge in the election for deputy leader and doubtless dreaming of a crack at the big one next time round.

And then, alone of the comparative heavyweights in apparently seeking nothing, is the angular, engaging and faintly enigmatic figure of David Miliband. If the gossip's right, it is the nightly wet dream of Tony, and above all Cherie, that Mr Miliband be press ganged into standing. The Birkenhead MP Frank Field, a renegade lone ultra on the Catholic right wing of the SGA (Stop Gordon Army) has called on him to mount a challenge, and for once Mr Field may be talking sense.

In the US, a fascinating battle is brewing between Hillary Clinton and Barack Obama a year before the first Democratic primary, with the winner odds on to become the 44th President. Mr Obama has barely announced his candidacy, but already the presence in the race of a smart, personable, charismatic young contender is electrifying American politics and encouraging passionate debate about the country's future. How desperately we need an Obama over here ... someone fresh and untainted, and with the nerve to challenge a front runner seemingly as impregnable as Hillary looked just a few months ago, to infuse a gruesomely stagnant political system with a bit of life.

Mr Miliband seems to agree. "In 2007 we have got to get our idealism back, to re-motivate ourselves and the country," he wrote in that New Labour house journal The Times earlier this week. "So we need to recover that sense of insurgency we had in opposition."

To me, despite his insistence that he supports Gordon, this looks like the dipping of a toe into the leadership pond. After all, only a fool could imagine Gordon Brown metamorphosing from prime creator of the status quo into idealistic insurgent by the simple expedient of moving a few feet next door - and Mr Miliband (First in PPE from Oxford; Kennedy Scholar at MIT; running the Downing Street policy unit before he was 30) is anything but a fool. So the cold logic of his words is that someone credible must run against Gordon ... and in the absence of anyone else, that someone can only be him.

If he were to run, he would start as a rank underdog, of course, but far from a no-hoper. The Bank of England's latest warning that interest rates may be hiked again must have made Gordon wonder about granting it its independence, because the relentless rise in mortgage repayments is a genuine threat to the chances of one whose electoral appeal depends solely on economic stability. With Mr Brown looking older and more shop-soiled by the week, the allure to Labour of taking on the Tories with an exact contemporary of David Cameron might become hard to resist.

There are other things about Mr Miliband than his youthfulness that appeal. He seems (forgive the lapse into technical politico-jargon, but sometimes nothing else suffices) rather nice. He is engagingly reticent about discussing the baby, Isaac, he and his concert violinist wife adopted in America two years ago, or the infertility nightmare that presumably preceded it. He is equally shy of cashing in on the sort of family history known today as "narrative", his late father Ralph - the Marxist historian who plays a similar role in this tale as Tony Benn does to Hilary - having come to Britain in flight from the Nazis.

It would be interesting to hear his thoughts on the ejection of the heckling Walter Wolfgang, another refugee from Hitler's Germany, from the Labour conference of 2005 under wilfully misapplied anti-terrorism legislation. But then we hear so little from Mr Miliband about matters not directly covered by his red boxes. Splendid as it was to listen to his adroit if patchy explanation of the Bernard Matthews Hungarian farrago, it would be even more enchanting if he expanded his range and told us what he believes in, if anything, other than the familiar social democratic melange rooted around a humanely tempered free market.

Having spent a morning reading his speeches, the impression is of a fearsomely bright technocrat - a Westminster version of one of those West Wing smartypants, with impossibly thick heads of hair and even more impossibly agile minds, who dart in and out of the Oval Office muttering "Mr President, we have a situation in Delaware".

Whether his reluctance to take on Gordon is evidence of cowardice, a calculation that Labour is doomed at the next election regardless of who leads it, or diffidence born of the realisation that leadership isn't his bag (as Dirty Harry sagely reminded us, a man's gotta know his limitations), there's no way of being sure. But the sense of dissatisfaction with how life in Britain has developed under New Labour is growing all the time - the visceral impact of the Unicef report on childhood cannot be exaggerated - making Gordon Brown's decade of duopoly ever more vulnerable to attack.

Mr Miliband's nickname, given to him by that lovable scamp Alastair Campbell, is Brains, after the cerebral Thunderbirds character who stayed on Tracey Island and did the thinking that enabled Virgil, Scott and the other brothers to defeat such lethal enemies as the beastly Hood (Gordon with an Alastair Darling eyebrow transplant). If he is merely a backstage nerd, so be it. Not everyone has the psychotic craving for ultimate power, and thank the Lord for that. However, you don't get to sit in a Cabinet, even as replete with pygmies as this one, before you're 40 without a dose of personal ambition.

So if that Times article (so quickly and conveniently followed by Mr Field's clarion call to arms) was the dainty dipping of a toe, then the time is close to belly flop into the pond. International rescue may be too tall an order, given the collapse of Britain's global reputation under Mr Blair, but is a little national debate about the country's direction under Labour really too much to ask?