How can a man who is 6ft 2in tall so often seem invisible? Indeed, how can the same man who speaks five languages struggle to be heard in any of them? This is the challenge facing Nick Clegg and the Liberal Democrats. Since becoming leader he has made the headlines only twice, first when he blurted out that he did not believe in God and then, last week, when he manufactured a position on a referendum on the Lisbon treaty that – even if the Almighty exists – He could not have salvaged.

It was appropriate that Lib Dem activists met over the past three days in Liverpool for their spring conference. That city peaked in influence during Victorian times and its hopes of sparking a revival this year through its European City of Culture status might be destined for disappointment. The cruel will claim that the same applies to the Liberals and their leader.

That would be unduly harsh. There is a respectable brief for the defence of Mr Clegg. He inherited an absurd stance on Europe from Sir Menzies Campbell that he thought it was impractical to ditch at short notice. He has already signalled a different approach to the public services – especially education and health – that releases his party from being the voluntary prisoner of the National Union of Teachers and the British Medical Association. He is also, crucially, making it plausible to speculate that if no single party has a majority in the Commons after the next general election, then he might back either Labour or the Conservatives.

This return to “equidistance” is vital to the credibility of the Liberal Democrats. In reality, Labour would be likely to offer Mr Clegg far better terms on electoral reform than the Tories and he would be mad not to strike that bargain. The Lib Dems can hardly afford to assume that hung Parliaments are like buses – you hang around for an eternity for one and then three arrive in succession. Yet he would be in a strong position to negotiate the best possible deal only if Gordon Brown feared that the Liberal Democrats might work with his rivals.

All of this is difficult to convey to the electorate. Seasoned sad types will have noticed some intriguing and original aspects to his conference speech yesterday but the remaining 99.9 per cent of the country will have missed them. At best, Mr Clegg will get the odd ten-second television clip of him banging on about a “new politics”. The trouble is that “new politics” is not new for the Liberal Democrats. Sir Menzies talked about “new politics”. So did Charles Kennedy. And Paddy Ashdown too. Sooty and Sweep might have done so as well and as far as the public are concerned Mr Clegg’s message is no more audible than Sooty’s. It is the eternal frustration of serving as the leader of the third party.

Mr Clegg is an inverse Barack Obama. The senator’s success is based on him controlling the words, themes and spotlight of the Democratic contest but with precious little evidence that he has any such dominance over political substance. The Liberal Democrat leader and his sympathisers have actually developed an impressive alternative definition of liberalism but cannot boil it down to a “yes, we can” formula.

Which is why, in this season of adopting and adapting American models, Mr Clegg should leave Hillary Clinton and Mr Obama to whom they belong, Mr Brown and David Cameron respectively. Counter-intuitively, perhaps, John McCain is a much more relevant example for Mr Clegg. There are three features of the Republican nominee’s political style that Mr Clegg could and should aspire to emulate.

The first is his relentless candour. A reputation for telling the truth even when it hurts him has been the absolute foundation of Mr McCain’s career. There is plenty of space in the market for this in British politics. That was the minor tragedy of the Liberal Democrat debacle over the referendum. To abstain in a Commons vote would normally mean that one was agnostic or neutral on the matter. Not one Liberal Democrat MP was sincerely uncertain over whether he or she thought a referendum on the Lisbon treaty would be desirable or essential. Mr Clegg must never again let himself articulate such a tendentious argument. He has to match the McCain straight-talk method.

Secondly, Mr Clegg must be prepared to be unpredictable. Mr McCain forced people to notice him by championing causes that are not expected from a Republican. He struck up alliances with Democrats on the reform of campaign finance, a hostility to the tobacco industry and climate change. It is this trait more than anything that explains his popularity with independents. Mr Clegg should be thinking beyond mainstream policy subjects to causes he cares about and where he can fight alongside others from the two big parties.

The final aspect is winning big by keeping small. When Mr McCain’s candidacy collapsed at the end of last summer he had no money and there was almost no media interest in him – familiar territory if you’re a Liberal Democrat. He did not resurrect his prospects by a national strategy aimed at impressing Washington opinion formers but through holding an astonishing 101 town meetings across New Hampshire at which he would answer anything. Mr Clegg has started in this direction but could do more.

None of this will instantly make him visible or be heard at full volume. His best chance, nonetheless, is to have frank and interesting things to say directly to the voters in Britain’s New Hampshires.

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