Matthew Norman: The change of leader that is the Lib Dems' only hope

Vince Cable is the antithesis of the model of a modern political general - and his party's last chance of remaining in the game at the next election

The Rt Hon Dr Vince Cable: an apology. Last December, in keeping with mainstream opinion among fellow commentators ("the poncetariat"), this column suggested that the Business Secretary was a vain and foolish old geezer who shot his bolt by showing off to a couple of young female reporters posing as constituents. I now wish to say sorry to Dr Cable for that hideous misjudgment.

Don McLean put it more elegantly in the lyrical paean to disregarded genius that he presciently entitled "Vincent". "And now I understand what you tried to say to me/ How you suffered for your sanity/ How you tried to set them free," goes the chorus. "They would not listen/ They did not know how/ Perhaps they'll listen now."

And perhaps they won't, because Cable seems cast as Westminster's own Van Gogh. Dishonoured and ignored when trying to flog such alarming portraits as Imminent Financial Armageddon and Evils Of The Murdochracy, he is deified as a visionary master only when the recognition comes too late to do him good. It's enough to drive a proud chap to hallucinogenic liquor and aural auto-surgery. So let it be stated, before Vince canes the absinthe and lops off a lobe, that it isn't too late at all. There is time for the Liberal Democrats, before they head into the starry, starry night of electoral oblivion, to recognise him as their route to salvation.

Reflecting on their recent leadership history, you'd guess that the appetite for missed opportunities was sated. If Charles Kennedy had been sober and engaged in 2005, when Mr Tony Blair was crippled by Iraq and Michael Howard by the dog-whistling manifesto authored by David Cameron, the Lib Dems might have vaulted the 100-seat barrier. Had Menzies Campbell not succeeded Kennedy, Vince wouldn't have been hamstrung by the "two bald buffers in a row" rule when Ming was removed. Had he run, he'd have won by a landslide after his sparkling turn as stand-in, and murdered Cameron and Brown in all three TV debates... his cadaverous causticity being the perfect contrast with the one's plump-cheeked callowness and the other's terminal state of denial about building the debt mountain as Chancellor.

If Vince was spot on about the perils of unaffordable personal credit, by Christ he was right about Murdoch. He suffered for his sanity over the latter, losing a chunk of his portfolio and very nearly his job for blurting that he hoped to set us free. But had he not defied Coalition pressure to refer the BSkyB takeover to Ofcom, as he justly enjoys reminding us, it would have been an irreversibly done deal long before the Milly Dowler story broke.

With his depleted political capital replenished by this vindication, Vince invests it with typical boldness. Whether they are listening to him now I slightly doubt. No previous soothsaying triumph opened Trojan ears to Cassandra's next prediction. But sod her for a moment, and join me in planting a big sloppy kiss on Vince's forehead for continuing to speak his mind with such wondrous bluntness.

Even Ken Clarke would quail at sourcing the current US debt threshold impasse to "a few right-wing nutters in Congress". But again Vince is correct, or sort of. Technically, the right-wing nutters are the Tea Party ultras whose proxy, or captive, the Republican establishment has become. John Boehner, the Speaker, and his GOP colleagues are too petrified of Tea Party primary challenges to compromise with Obama. The Prez offers cuts to social welfare programmes, asking in return only that the smaller part of the deficit reduction come from tax rises for the wealthy. Knowing that the Tea Party would go berserk if he agreed, Mr Boehner refuses. If no deal is struck by Tuesday's deadline, the US will default on its debts with barely imaginable consequences for the world economy.

Presumably some short-term fudge will postpone the apocalypse. But the danger posed to every one of us by right-wing nutters is horrendous, and no other senior British politician has shown the guts to state it plainly. In fact, Vince might have gone further by sourcing this surreal crisis to the twin forces against which he has lately declared war. The bankers – the "spivs and gamblers" whom he is again fighting Treasury resistance to bring under control – lit the inferno. Now Rupert Murdoch stokes it, via Fox News, inflaming Tea Party mania to such white heat that the Republican establishment is melted into doing its deranged bidding.

Vince could go further still. If he fancied giving a major speech on the historic threat of right-wing extremism in times of grave economic terror, as he should, he might identify the Norwegian monstrosity as part of the same continuum. The right-wing nutter responsible was influenced by the musings of Melanie Phillips, a regular guest on Glenn Beck's thankfully defunct Fox show. Mr Beck's response to the horror is to liken the summer camp attended by those sweet, innocent Norwegian kids to a Hitler Youth rally. Sometimes, there are no words.

Most of the time, however, there are words, and Vince Cable usually finds the right ones. He is neither collegiate nor a cunning political strategist. His tongue is unguarded, his edges unsmoothed. He is the antithesis of the model of a modern political general. And he is, as I said, the Lib Dems' last chance of limping out of the next general election with enough seats to remain in the game.

Nick Clegg's flush was busted the second he sat beside the PM nodding frantic approval of the tuition fees he had vowed to resist. If that is self-evident, it should be equally obvious that he should stand aside for the only centre-left politician with a powerful national voice to set against the orthodoxy with which, on this latest dismal growth figure, George Osborne is leading us into the dreaded double dip. No one else, Mr Clegg least of all, has the integrity and public trust to revive a moribund political force by lending it distinctiveness from its senior Coalition partner.

A party prepared to sleepwalk to disaster rather than endure the agony of removing a zombie leader commits suicide. Labour under Mr Brown confirmed this, but had no natural replacement. The Lib Dems have no such excuse. They have the outstanding British politician of the age in front of their eyes. If they lack the sense to see this or the will to act on what they see, they will sign their own death warrant and deserve their execution.