The International Olympic Committee on Tuesday approved an unusual proposal to name two winners in the Summer Games bidding race between Los Angeles and Paris.
Gathering at a meeting in Switzerland, IOC members unanimously agreed to the idea of awarding 2024 to one city and 2028 to the other.
The decision all but assures that Southern California will get the Olympics back for a third time.
The IOC just has to convince either L.A. or Paris to go second.
French bid leaders have repeatedly pushed back against the idea of waiting, so it has been widely expected that L.A. would agree to take 2028.
Moments after the vote was taken, Mayor Eric Garcetti and Paris Mayor Anne Hidalgo appeared onstage, interrupting the proceedings.
"Thank you," Hidalgo said.
Garcetti added: "Can we just say thank you?"
The mayors summoned IOC President Thomas Bach to join hands in triumphant salute to the membership.
Negotiations with the two cities had already begun in preliminary fashion but will now turn more serious in coming weeks.
"We take nothing for granted," Garcetti told reporters at an ensuing news conference. "Our job now is to work with the IOC, to forge a path forward for our city and for the future of this [Olympic] movement."
Bach suggested that talks could begin in earnest as early as Tuesday evening when he joins the mayors for dinner, but he did not expect an immediate resolution, saying: "I just hope in August we could be there if everything is going well."
If nothing else, Garcetti said he would need to discuss the situation with the Los Angeles City Council, which previously voted its unanimous support for a 2024 bid. The mayor said he had already been in contact with council President Herb Wesson, describing Wesson as "excited."
In an interview with the Los Angeles Times last week, Bach expressed his desire to reach an agreement before the final selection, which is scheduled to be made at a mid-September session in Lima, Peru.
The candidate city that agrees to go second could be in position to ask for concessions, including a larger slice of IOC revenues.
At a time when numerous potential hosts have backed away, concerned about the billions of dollars required to stage the Games, it would behoove the Olympic movement to secure two strong candidates through the next decade.
If no deal can be reached, the IOC voted to proceed with a normal election, choosing only a winner for 2024.
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10:30 a.m.: This article was updated with background information and quotes from Eric Garcetti and Thomas Bach.
8:55 a.m.: This article was updated with Eric Garcetti and Anne Hidalgo appearing onstage after the vote.