The International Olympic Committee has announced rules have been altered to allow every city bidding for the 2024 Olympics to make it to the final vote.
In the past a shortlist would have be announced before the final vote.
But the change opens the possibility of as many as seven cities battling it out over a two-year global campaign.
The deadline for the official submission of bids is 15 September with the declared candidates so far being Paris, Rome, Hamburg and Budapest.
Boston withdrew from the race last week because of a lack of public support, but the US Olympic Committee is still planning on entering a city, with Los Angeles considered the likely choice.
Toronto and Azerbaijan's Baku are also said to be considering bidding.
Christophe Dubi, the IOC's executive director of the Olympic Games, said: "We could not really use the same cut as we used in the past. It would be unfair to say there will be a cut, an artificial one. We have to change the way we do things."
The vote will be held in Lima, Peru, in September 2017.