With the Italian capital, among the frontrunners, out of the picture as the country slashes public spending amid wider eurozone concerns, Tokyo, Madrid and Istanbul complete the list of bid cities.

"The IOC will be looking at numbers very carefully this time round, especially now, after Rome," said an Olympic consultant involved in many past Olympic bids, speaking on condition of anonymity.

"They will be looking at finances closely and they will also be thinking whether other parts of the world make more financial sense at the moment although only a few weeks ago they may have appeared like a long shot."

A day before the International Olympic Committee collected all candidacies, Italian Prime Minister Mario Monti said on Tuesday Italy's difficult economic situation would prevent the government offering the necessary financial guarantees for a possible Rome Olympics.

"The decision of course must be respected but in my view the Italian government missed the chance to send a signal for economic growth in Italy," IOC Vice President Thomas Bach told Reuters on Wednesday.

"It is a pity that the obvious outstanding bid preparations will now be wasted. But the field of candidates remains strong," Bach said.

The IOC will elect the winning bid in Sept 2013 at their session in Buenos Aires, Argentina.

WISE DECISION

"I think it was, under the circumstances, a very wise decision for Italy," IOC marketing chief Gerhard Heiberg told Reuters.

"The IOC regrets this because we would have liked Rome to bid but I understand very well the reasons for this. It is a purely Italian case," said Heiberg.

"I think Spain has decided to go after the Games. That is what I feel and I hope they will stay in the race," he said of the only other eurozone country bidding.

With the IOC demanding water-tight financial guarantees and state backing long before the Games are even awarded to a city, Madrid, bidding for the third straight time, will be feeling the heat as the country struggles to contain growing unemployment and a wide budget deficit.

"That is inevitable," said Danny Townsend, of brand analysis and research company Repucom International. "(Rome's withdrawal) is symptomatic of the financial situation that is engulfing Europe."

"At the end of the day these people are paid to make decisions for the good of the country," Townsend, Repucom's Europe, Middle East, Africa and South Asia President, told Reuters.

"If the strategy for Madrid is that by hosting the Games they will be a catalyst for a financial revolution then that is fantastic," he said.

"They (Madrid bid) have legitimate reason to view this expenditure as legitimate for the city. But it comes at a cost. Italy took a completely different decision," Townsend added.

GOING EAST

As for the possibility of the Games going east straight after the first South American foray in Rio de Janeiro in 2016, Townsend said that trend was already there and would only continue but traditional markets like Spain and Italy remained very attractive.

"The Games will naturally and inevitably head into that direction. The trend is there, to reap benefits of natural resources," he said.

Both Qatar, the world's top liquefied natural gas exporter and Azerbaijan's booming capital Baku, flush with the proceeds of oil and gas sales from reserves in the Caspian Sea, are aggressively going after global events.

The Gulf state has already been awarded the 2022 soccer World Cup and has been investing heavily in attracting major sports events to Doha.

It will be the city's second successive Olympic bid after failing to make the cut for the 2016 Games. Baku also failed in the first hurdle for 2016.

At the time it was Doha's plan to stage the Games in September/October that killed their bid.

This time round the IOC has already approved the change in dates from the usual July/August slot and the country's readiness to spend the billions needed for the biggest multi-sports event in the world makes them an attractive choice.

Istanbul, bidding for the fifth time in the last six bids, is also highlighting Turkey's sharp economic growth last year of about 8.0 percent as proof that the country can shoulder the financial burden of the Games.

(Reporting by Karolos Grohmann, editing by Justin Palmer)

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