Matthew Norman: So Gordon is not that clever after all ...

"You Can Get It If You Really Want It" was the studiedly optimistic musical message as David Cameron left the stage in Blackpool on Wednesday afternoon, but the lyric on everyone's mind belongs to a slightly edgier singer than Jimmy Cliff.

A certain Clash single has already been given its ritual run out on Newsnight, and in seeking guidance Gordon Brown might look beyond the title of a song written by a man whose coffin will have corkscrewed to the earth's core at the sight of a Labour PM slavering over Mrs Thatcher. "Should I stay or should I go now?" as Joe Strummer put it in the chorus. "If I go there will be trouble/ An' if I stay it will be double."

From beyond the grave, Mr Strummer puts his finger on the crux of it. Where a few days ago Gordon must have expected to take this decision from a position of enormous strength, the election timing begins to look more like a choice between the lesser of two evils.

Unless it's as blatantly calamitous as Suez or the ERM, identifying a single political event as the catalyst for a leader's demise is a dangerous game. Yet sometimes a vignette can be revealing enough to implant in the national mind an acorn of subliminal concern that might just grow into a mighty oak of doubt, disdain and even distaste. Gordon's jaunt to Basra may prove that vignette.

It certainly wasn't a cataclysm, and it won't cost him his job, but it was his first serious error in office, and one so crude and clumping that it's barely credible he made it at all. So inevitably would his claim of a troop withdrawal from Iraq of 1,000 be instantly revealed as cheap trickery that you half wonder whether it was an accident; or whether on some level, like that toilet-cruising US Senator with the cubicle-straddling leg stance, the Prime Minister wanted to be caught. One can certainly see how the subconscious of so pathologically cautious a man might manufacture an excuse to avoid a snap election.

That's the charitable explanation. The harsher one is that Gordon, as some have long feared, is little more than a less ostentatiously monomaniacal version of the man he replaced ... a politician who talks in grandiose, high-minded, global strategic generalities, but thinks only of footling, short-term, parochial tactical gains.

Today, the focus groups will be gathering across the country to offer their insights over Pringles and warm Jacob's Creek, but if they're anything like the focus group of one in this house the findings will not be helpful or encouraging for Gordon. Like so many women, my wife developed something alarmingly like a schoolgirl crush on him the moment he moved next door in June, and would no more brook questioning of her sweetheart's perfection than she'd have tolerated criticism of Les McKeown as a 14-year-old Bay City Rollers fan. Any attempt to challenge her adoration was met with a shushing finger to the lips, or even a growl, until Tuesday. "I'm starting to have my doubts," she morosely confessed during a TV report on the Basra trip and the massaging of that troop reduction figure. "Isn't the point to Gordon that he doesn't go in for stupid games and chicanery like Blair? The whole point of him is that he just gets on with the job."

I didn't make the point for fear of intruding into private grief, but to Gordon chicanery and getting on with the job are one and the same thing – that regurgitating the same numerical promises, whether on NHS investment, troop numbers or whatever, has been his signature dish for a decade. Disguising this, he rode his luck quite brilliantly for the first three months. As the various scares (airport bombs, foot-and-mouth, Northern Rock) fizzled out without becoming real crises, he struck a perfect pitch of reassuring gravitas. The only sound audible on Tuesday evening, however, wasn't the gruff baritone of protective paternalism, but the faint whistling of a giant penny beginning to drop from a great height.

As a quick response to this first sign of an incipient fall from grace, meanwhile, David Cameron's speech on Wednesday could hardly have been more elegantly nuanced. One could have done without the Leslie Welch impression (a fine memory is a useful tool, but no one loves a show-off), and the "We will fight. Britain will win" crescendo provided an off-putting echo of Michael Portillo's SAS-inspired gibberish. Even so, this was a genuinely thoughtful and – to nick Tory HQ's buzzword du jour – balanced piece of oratory, offering the delegates (the nutters in the country) a little red meat without provoking a feeding frenzy, and eschewing the pyrotechnics in favour of gently assuaging fears of that much predicted rightward lurch.

Cute as it was, the speech and the unexpectedly serene conference it concluded won't reverse Labour's entrenched opinion poll lead, and may trim it by no more than a couple of points. Yet nebulous as this will seem in comparison with the hard statistics currently being compiled by the private pollsters, one senses enough of a shift in the public perception of both leaders to leave Gordon's cuticles more gnarled than ever on Monday morning.

If he calls the election now, the psephology all but guarantees a win (the Tories require an unimaginable lead even to form a minority government), while one assumes Gordon has cheap but shiny electoral bribes hidden all the way up his sleeve. Income tax cuts, further (and possibly genuine) troop reductions, more defections, trumping the Tories on inheritance tax reform, even a referendum on the EU treaty (portrayed not as a U-turn, of course, but as evidence that he is listening) ... the man is such an opportunistic scoundrel that nothing is beyond him. But the needlessness of calling an election he cannot lose will make him look panicky, and the fiction of the faithful old Father Brown plodding on with the job at hand, which took such a hit in Iraq, will further unravel. The victory could well fall on the Pyrrhic side of narrow.

If he delays, on the other hand, he not only reinforces the old image of the nervous Nellie who could never quite summon the courage to kill off Blair. He also faces the seemingly imminent prospect of a stagnating housing market damaging consumer spending, allows Mr Cameron time to entrench the resurgence he hinted at this week, and risks deepening the disillusionment now stirring for the first time in the hearts of Gordon groupies like my wife.

It's a very fine calculation, and I wouldn't bet a fiver at even money which way he will decide, but overall it seems to me that Joe Strummer was right. Going to the country is dangerous enough, but staying in Downing Street means double trouble for Gordon Brown. For all the wrong reasons, he should go now.