International Olympic Committee President Thomas Bach sits between Los Angeles Mayor Eric Garcetti and Paris Mayor Anne Hidalgo at a news conference Tuesday in Lausanne, Switzerland. Committee members voted Tuesday to work on a deal in which one of the two cities will host the Olympics in 2024 and one in 2028. (Pierre Albouy/Reuters)

Los Angeles, California, and Paris, France, have their Olympic hosting destiny in their own hands. If they can agree who goes first, each city will be awarded either the 2024 or 2028 Summer Games in September.

International Olympic Committee (IOC) members voted unanimously Tuesday to seek a three-way deal between the two bid cities and the IOC executive board. Talks will open with Paris widely seen as the favorite for 2024.

If a deal falls through, only the 2024 hosting rights will be voted on when the IOC next meets, on September 13 in Lima, Peru.

However, an agreement seemed assured, judging by the reaction of the two mayors.

“I have full confidence that we will get there,” L.A. Mayor Eric Garcetti said at a celebratory news conference in Lausanne, Switzerland, for both candidates and IOC President Thomas Bach.

Paris is favored to get the 2024 Games. The city hosted the Olympics 100 years earlier. (Gonzalo Fuentes/Reuters)

Garcetti and Anne Hidalgo, the mayor of Paris, had emerged on stage seconds after the vote, holding hands, to welcome the decision. They were joined by Bach, who raised an arm of each in a shared gesture of triumph.

French President Emmanuel Macron was in Lausanne to promoting the Parisian cause — in a closed-door session with IOC members to explain how they would host the 2024 Olympics.

The presidential push was judged necessary by Paris, which has failed with three recent Olympic bids.

“We lost three times, we don’t want to lose a fourth one,” Macron said at the news conference. “I’m here to convey the message that there’s a strong unity to back this candidacy.”

Minutes after Macron spoke, President Trump wrote on Twitter: “Working hard to get the Olympics for the United States (L.A.). Stay tuned!”

Even without help from heads of state, Los Angeles and Paris are likely to reach a deal. A head-to-head fight for 2024 would create a loser that is unlikely to return four years later for a new 2028 bid contest.

“Both of us will find it more and more difficult to convince cities — whether it’s Paris, Los Angeles or other American cities — to really go into this process if one of us gets turned down,” Garcetti had said earlier Tuesday.

A deal to make both cities winners would fulfill a strategy that Bach set in motion last December to help safeguard a stable future for the signature Olympic event.

Asked when a 2024-2028 agreement could be sealed, Bach suggested: “If you ask me, I hope that in August we could be there.”

The IOC approved the expected double award after hearing both cities present their 2024 hosting plans at a conference center in its home city.

Both cities used 45 minutes of videos and speeches in a closed-door session with IOC members to explain how they would host the 2024 Olympics.

At separate news conferences, the mayors said they could work toward a deal.

“We look forward to working together, maybe not in competition but collaboration with Paris,” Garcetti said.