By the end of this month, the Government will decide whether to back a bid to bring the 2012 Olympics to Britain.

Nick Morrison asks if success would make us the envy of the world, or land us with a financial albatross.

IT'S the greatest show on Earth - and it will enrich the life of the nation beyond measure. It's a chance to dazzle the world with our organisational expertise; create a legacy of unrivalled sporting facilities; unite an entire nation behind our heroes; enthuse the indolent to take up sport and provide the springboard for regenerating areas of deep deprivation.

Given this, bidding to bring the Olympics to Britain for the first time in more than 50 years should be a no-brainer. No other event provides such an opportunity to both make a worldwide impact and to bring widespread and long-lasting benefits. You only have to look at the way Sydney grasped its chance with both hands in 2000 to see how a city can make the most of hosting the Games.

But the Government is dithering over lending its support to bring the Games to London in 2012. And without Government backing, the bid is almost doomed to end in failure.

A committee of backbench MPs will give their verdict on the bid later this month, and by the end of the month the Government will announce its decision. But the omens do not look good. The committee's chairman, Gerald Kaufman, has already said it would be "madness" to bid for the Games, and Culture Secretary Tessa Jowell said it was important the Games did not become "a dead anchor".

At the forefront of the Government's mind are concerns that a campaign to secure the Games would prove expensive and lead to endless negative publicity. And with the fiasco over the Millennium Dome still lingering, not to mention the chaos over the new Wembley stadium and the aborted Pickett's Lock development, putting Britain's ability to host major events to the test may not seem like a good idea.

There is also the very real prospect that a bid would prove unsuccessful in any case. With Paris, New York and Moscow likely to be in the race - and Paris emerging as the front-runner - losing out would hardly cement Tony Blair's image as an admired statesman.

But, despite the drawbacks, a successful campaign could bring huge rewards, according to Dr Peter Warburton, director of sport at Durham University. And you only have to look to last year's Commonwealth Games in Manchester for a taste of the riches on offer.

"The Commonwealth Games was a huge success and it has left Manchester with a massive legacy of sports facilities, although whether we are using them effectively is another question. One of the few 50-metre pools in the country is not being used for high performance swimming, but is now in 25-metre blocks for community use," he says.

Dr Warburton says the failure of previous Olympic campaigns by Manchester and Birmingham have shown that London is the only British city able to mount a credible bid, but the capital's infrastructure problems, with a creaking Underground and gridlocked overground, present a major obstacle.

But for the bid's supporters, who include London mayor Ken Livingstone, the Games represent a chance to regenerate a deprived community. If the Games came to London, they would be concentrated in Stratford in east London, and, as well as necessary transport improvements, would bring much needed housing in the shape of an Olympic village of some 4,000 homes.

Against this, critics say the same number of jobs and business could be created for £500m, small beer compared with the estimated £5bn plus to bid for and stage the Games.

But for the competitors themselves, the key issues are not the costs and material benefits of the Games, but the pride of competing in your own country. This is something Karen Dixon, a three-day eventer from Barnard Castle in County Durham, has witnessed at first hand in four Olympic Games.

"It would be the ultimate, because you would have tremendous support and it would be a really prestigious event for all the Brits," says Karen, who won team silver at Seoul in 1988 and had a highest individual finish of fifth at Atlanta eight years later.

"In Sydney, the support for the Australians was incredible and there was a real feeling of camaraderie among the Aussies, which was really something."

The success of the Sydney Games has indeed left a hard act to follow, but that, too, has not been without its price. While every Games since Los Angeles in 1984 has made a profit, Stadium Australia is struggling to attract the major events which will help pay its way.

It's true that the Olympics does lift the profile of sport, but this happens wherever it is held. And the burst of enthusiasm for hockey after the men's team lifted gold in Seoul shows that it is success which brings interest, not necessarily playing host.

And sceptics argue that Australia's spectacular medal haul in the Sydney Games was not entirely down to home support, but was the culmination of a 25-year strategy to reach sporting success after picking up a solitary gold in Montreal.

But while the Government may see lending its support to a bid as a high risk manoeuvre, derailing London 2012 leaves the Prime Minister open to the charge that he lacks ambition and chooses to play it safe rather than take a gamble.

Tory leader Iain Duncan Smith has already sensed a weakness, and accused Mr Blair of being petrified, suggesting that the advice of Hartlepool MP and former Dome supremo Peter Mandelson was to avoid the bid like the plague.

Downing Street is said to have drawn up a contingency plan to counter accusations that it is letting down British sport, in the shape of £250m to help elite athletes. But while this may help those at the top end of the scale, it may be that only the Olympics themselves can make the sort of difference to sport that Dr Warburton sees as a necessity.

"Apart from soccer, sport in this country is in big trouble financially. There is an argument that if you are going to invest money, why not invest in the grass-roots infrastructure? But if the Government doesn't go for the Olympics it won't spend the money on the infrastructure anyway," he says.

"If they're not going to put that kind of money into the Olympics, will they put it into sport? The answer is no. I believe if we don't host then no more money will be put into sport.

"In fighting your corner for sport, you take what you can get, and, as someone involved in sport, I would go for it. There are a lot of pitfalls, but you gain nothing by not going for it, although if someone said would I take the money for the Olympics or for sport I would say for sport every time."

With the Cabinet debating the issue on January 30, the signs are that ministers will reject a campaign. If they do, it will not just be a sign of a lack of faith in our ability to bid for and stage the world's biggest sporting event, but will say much about the limits to the Government's ambitions. Is this a Government prepared to take a gamble, or one that prefers to play it safe?