Matthew Norman: At this rate Ed Miliband will be in Number 10 by default

The ritual disclaimer that Cameron is too clever to be underestimated begins to look outmoded

Painful though it is to pose the question with your ironic disdain audible as I type it, posed nonetheless must it be. Has the moment come seriously to consider the prospect that Ed Miliband will be our next Prime Minister? I know, I know. This question, which I along with everyone else have answered in the negative before, strikes you as a makeshift application to be sectioned. Had Edmund Blackadder asked it in lieu of sticking two pencils up his nose and wearing his knickers as a hat, even General Melchett would have seen him cosily ensconced in a psychiatric ward by the time Baldrick, Percy and Captain Darling went over the top.

The received wisdom on the matter demands the briefest reiteration. Forget the calamity in Bradford West, it contends. The younger of Labour's fraternal droids is such a nerdy, drippy, Ed-enoidal no-hoper that he couldn't lead the Free Mansions And Lamborghinis For All Party to victory in Soweto against the Necklacing Alliance fronted by Eugene Terre'Blanche's ghost. And yet behold, here we find the loser of losers sitting on a double-digit advantage in one new poll, and up by 9 per cent in another. What can snapshots of voting intentions taken years ahead of the vote possibly tell us, you may ask, about Little Ed's ability to win a general election? Absolutely nothing. Michael Foot and Neil Kinnock consistently had larger leads over Mrs Thatcher, and were routed.

Yet that strikes me as the wrong question at this monumentally dismal and apathetic political moment, the right one being this. What do these vignettes of public mood tell us about his ability to lose a general election less disastrously than the enemy? Could he become Prime Minister by default, much like the incumbent, simply by being slightly less off-putting a presence than his rival? Might his optimal strategy be to accept his own presentational difficulties and the fearsome lack of interest in national politics by keeping his trap shut, and leaving the Government to continue its super slo-mo implosion?

After two years of giving the Coalition all the benefit of every doubt, the punters appear finally to be exhausting their stores of indulgence. Their tax-free charitable donations are running out, and if these polls could be converted into one sound, it might be the thud of a gigantic penny dropping (in this case, on to David Cameron's cunningly concealed bald spot). The sequence of blunders over which the PM has latterly presided – most arising from the Budget, but with the cobblers about electronic surveillance lending the incompetence impressive range – has been startling, and the speed of his U-turns dizzying. Even when a policy is broadly popular and correct – what gives anyone the right to spend their taxes as they choose? – he is so scrambled by the cumulative post-Budget contempt that he pirouettes in a flash.

The ritual disclaimer that Mr Cameron is too clever, versatile and polished to be underestimated begins to look outmoded. Much of the smooth public relations operative gloss remains. But enough has been stripped away to allow a peek behind the veneer, and more and more there seems less and less to him than originally met the eye. The football chant that perhaps captures the nascent public feeling is the one reserved for the manager of a relegation-threatened side after a particularly obtuse substitution: you don't know what you're doing.

If it is still too early to lampoon Mr Cameron as Steve McClaren, bemusedly wandering up and down the Downing Street dugout beneath his brolly, there is no sign whatever of the political and economic weather improving. The most alarming polling figure published this week was not the broad one about voting intentions, the Labour lead being as soft and biodegradable as the squidgiest pasty. It wasn't even YouGov's finding that Ukip has more support than the Liberal Democrats, though this represents a graver electoral threat to Mr Cameron than to Nick Clegg. It is that Ed Balls is now as well trusted to run the economy as George Osborne. God have mercy on the Tories if Mr Miliband's most lethal liability is on his way to establishing a lead over a Chancellor seen a few weeks ago as among Mr Cameron's greatest assets.

Making long-range psephological predictions is an imbecile's game, and the only one worth risking today is that, with core supporters of all three main parties as disaffected as they have ever been, turnout at the next election will be heartbreakingly low. The only vaguely reliable guide to the outcome, as always, is professional betting money, and the current favourite on Betfair is no majority for anyone.

Amid all this opacity, one thing is increasingly clear even if the Poncetariat of pundits to which I have the honour of belonging, not to mention his colleagues, refuses to acknowledge it. For all the geeky looks and whininess of tone, Ed Miliband is a cannier and more able Opposition leader than the lazy caricature as feckless nebbish allows. Snort with derision by all means. But if he keeps fairly shtum and invisible, and leaves this government to do his work for him, in this political Bizarro World where victory means losing marginally less horribly than the other guy, that might just about be enough.