Even though the race hasn't officially started, the field for the 2024 Olympics is getting more crowded by the day.
A proposed Paris candidacy was approved by the city council today, a major step toward finalising a bid to bring the Games back to the French capital for the first time in a century.
Paris, expected to get the final go-head in June, would join a race that already includes declared candidates Rome, Boston and Hamburg, Germany.
Bids from a handful of other cities could also come forward before the Sept. 15 deadline set by the International Olympic Committee.
That will sound the starting gun on a two-year global campaign that will climax with the IOC vote in Lima, Peru, in 2017.
The contest shapes up as a battle between Europe and the United States - if the faltering Boston bid manages to stay afloat and survive a referendum in 2016.
A look at who's in, who might be in, and how the race is developing:
OUI TO PARIS
The last time Paris hosted the Olympics was 1924. The symbolism of hosting the games 100 years later is potent.
After failed Paris bids for the 1992, 2008 and 2012 Games, and a disastrous French bid from Annecy for the 2018 Winter Games, France is taking its time to build domestic support.
With Monday's endorsement by the city council, the bid now needs only the official authorisation from the national government. That seems a fait accompli as President Francois Hollande has already given his blessing. He'll brief IOC President Thomas Bach on the project during a visit to Switzerland on Thursday.
The bid is expected to be led by Bernard Lapasset, who heads the French Committee for International Sport, and French IOC member Tony Estranguet.
The infrastructure budget for a Paris Olympics has been estimated at 3 billion euros ($US4.5 billion), with operational costs of 3.2 billion euros ($US4.8 billion).
If Paris wins, it would become a three-time host. It first held the games in 1900.
Status: On the up.
Rome is another European capital seeking to host the Olympics again after an absence of decades.
The Eternal City, which staged the 1960 Games, announced its bid in December. Two years ago, Rome was forced to withdraw its bid for the 2020 Olympics when the Italian government pulled the plug at a time of financial austerity.
While the Italian economy is still stagnant, all sides - including Premier Matteo Renzi - seem on board this time with what they describe as a cost-conscious budget.
Former Ferrari president Luca Cordero di Montezemolo has been chosen to lead the bid.
The bid is expected to include many of the venues used in 1960. Officials have raised the possibility of holding events at the Vatican, such as archery in St. Peter's Square.
Rome has projected its Olympic costs at $US7.5 billion, $US2 billion of which would be covered by the IOC.
BOSTON OR BUST
Boston's bid has floundered ever since the Massachusetts capital was put forward as the U.S. candidate in December over Los Angeles, San Francisco and Washington.
The U.S. hasn't hosted the Summer Games since Atlanta in 1996, and many Olympic officials felt the time was right in 2024 after defeats for New York (2012) and Chicago (2016).
But there has been more opposition than enthusiasm for the bid in Boston, where residents feel they were kept in the dark by the process and fear they will be left footing the bill.
After a recent survey found only 36 percent of Bostonians are in favour of hosting the games, officials decided to put the bid to a referendum in November 2016. The bid will be in limbo until then, with the prospect of dropping out midway through the race.
The northern port city of Hamburg was chosen over the capital city of Berlin as the candidate to bring the Olympics to Germany for the first time since Munich held the 1972 Games.
Hamburg will face a referendum later this year, a crucial test in a country where Munich was forced to scrap a planned bid for the 2022 Winter Games after it was rejected by voters.
A recent poll showed 64 percent of Hamburg's residents back the bid, but opponents are already campaigning against it.
Germany also wants to host the 2024 European soccer championship, and it's unlikely the country could be awarded both events.
INTEREST FROM INDIA
Bach will visit India later this month amid speculation of a bid by the world's second most populous nation.
Indian media say Prime Minister Narendra Modi is keen on putting forward Ahmedabad, the biggest city in his home state of Gujarat, as the potential host.
India's organisation of the 2010 Commonwealth Games in New Delhi was heavily criticised at home and abroad over corruption charges and construction delays.
Status: A stretch.
-Hungary is exploring a possible bid from Budapest, which has tried unsuccessfully several times for the Olympics, including the1920, 1936 and 1960 Games.
-Turkey is waiting until after national elections in June before deciding whether to mount another candidacy from Istanbul, which failed in bids for five of the last six Olympics.
-Baku, the capital of Azerbaijan, is hosting the inaugural European Games in June and could follow with another Olympic bid after failing to make the cut for 2016 and 2020.
-The Qatari city of Doha also failed to make the finalists for '16 and '20. It may skip the 2024 race with another Asian city, Tokyo, hosting the 2020 Games.
- South Africa is now focusing on hosting the 2022 Commonwealth Games in Durban and unlikely to bid for the '24 Olympics.