America decides: Can Mitt Romney get his groove back?

It's set up for the Republican to win –but his campaign just won't catch light. So can the party convention finally get Mitt in the game?

Pity poor Mitt Romney. Right now, everything should be going his way: a highly vulnerable opponent, forced to defend the most anaemic recovery from a recession in three-quarters of a century, and excitement building ahead of one of American politics' defining rituals, the Republican National Convention in Tampa, that will formally nominate him as Barack Obama's challenger in November.

But there's no reckoning with Sod's Law. The listless economy, the soaring federal debt and the 8 per cent-plus jobless rate should be the talking points of the hour. Instead a fuss kicks up about a Republican Congressman who went skinny-dipping in the Sea of Galilee during a boozy 2011 junket to Israel. Then an even more damaging one erupts, threatening to split the party, as a key Republican senate candidate raises the bizarre concept of "legitimate rape", and turns the spotlight on the party's controversial (many would say antediluvian) efforts to ban abortion. And now the whole Tampa show could be thrown into chaos if – as forecasters warn is possible – Tropical Storm Isaac, currently churning into the Caribbean, arrives in south Florida along with thousands of Republican conventioneers on Monday as a fully fledged Category Two hurricane.

The unpredictable events listed are, of course, not the only reason Mr Romney has been underperforming, trailing not just in national polls but in the eight or nine swing states where the election will be won and lost. He may look like a casting candidate for Mount Rushmore. But he's been a dismal campaigner thus far, stilted and oddly passive, scripted in everything he says, yet somehow always prone to the unfortunate remark.

As a result, Americans still hardly know Mr Romney. Salvoes of ads from the Obama campaign since early summer have largely defined him, and not flatteringly: as the corporate vulture from Bain Capital, a multi-millionaire who manages to pay very little tax, who changes his views on everything, and who has no idea of the problems faced by ordinary folk. Right now, his personal approval ratings languish at barely 40 per cent, according to the latest Washington Post/ABC News poll, among the lowest ever recorded for a candidate at this stage of the game.

The convention is Mitt Romney's great opportunity to paint his own portrait. It's easy to say conventions don't matter any more, that they're just four-day party infomercials, choreographed down to the last second, of which the networks no longer bother to accord prime-time coverage. And indeed, not since August 1976, when Ronald Reagan was challenging President Gerald Ford, has one opened amid genuine uncertainty about who would be the eventual nominee.

True, they can produce wonderful oratory (for instance Ted Kennedy in 1980, Jesse Jackson in 1988 and a certain Illinois state senator in 2004). Rarely, though, are they remembered for the actual nominee's speech – the exception being George H W Bush's pledge of "Read my lips, no new taxes" in 1988, which may have won him the election that year, but the abandonment of which helped defeat him in 1992. Tampa 2012, however, could be different. For sometimes conventions are watersheds.

Take that same year of 1992. A scandal-tarred Bill Clinton limped into the Democrats' New York convention, with a sceptical country unconvinced he was up to the job. Four days later, he stormed out of Madison Square Garden on to the campaign trail. The invigorating and expertly staged proceedings gave the youthful "Double Bubba" ticket of Mr Clinton and Al Gore a massive and lasting bounce in the polls. In more modest fashion, Mr Romney hopes to do the same in Tampa.

"The American people probably aren't going to fall in love with Mitt Romney," House Speaker John Boehner admitted a few weeks back. Rarely has a truer word been spoken, given how the candidate's wealth and his Mormon background set him apart from most of his countrymen.

Certainly, Mr Romney's choice of the brainy and dynamic Congressman Paul Ryan as his running mate has injected some pizzazz into proceedings (and given him a small boost in the polls). Moreover, the visibly excellent personal chemistry between the two – by no means always the case on presidential tickets – may sharpen Romney as a political performer. But he remains an intensely private man, who will never be a crowd-pleasing barnstormer.

Instead, two themes will run through Tampa, alongside the obligatory round-the-clock lambasting of Mr Obama. One will be an attempt to humanise the candidate. Expect a procession of friends and family, and a stream of warm and fuzzy personal anecdotes – and not just about how the Romneys once went on holiday with their dog strapped to the car roof.

The other theme, even more important, will be the showcasing of Romney the problem-solver, the businessman with the skills needed to get the country back to work, and the budget deficit under control. Not Romney the heartless corporate raider, but Romney the manager who fixed the 2002 Winter Olympics in Salt Lake City, with the ability to work with the other side that made him an effective governor of the overwhelmingly Democratic state of Massachusetts.

In short, not necessarily a loveable Mitt Romney but at least a likeable one, worthy of respect and admiration, and the man America needs at this difficult hour.

It may not work, of course. With the tax-cutting, government-slashing Mr Ryan to aim at as well, Democrats will devote even more energy to depict "Romney/Ryan-onomics" in class war terms, a strategy to reduce benefits for the poor and middle-income earners to finance lower taxes for the already wealthy. Then there is the eternal problem of Mr Romney's healthcare reforms in Massachusetts, model for the "Obamacare" he now vows to repeal. Or the convention could simply be a snooze.

A successful one, however, could alter the dynamic of the campaign. Team Obama might be placed on the defensive, its ad assaults would risk coming across as nasty and dishonest sniping. Mr Romney by contrast would enter the final phase of the campaign with the wind in his sails – not to mention a greater financial war-chest.

But it all depends on Tampa.