French President Emmanuel Macron (3rd L), Paris 2024 Olympic bid co-president Tony Estanguet (4th L) attend a press conference after the presentation of the Paris 2024 Candidate City Briefing for International Olympic Committee (IOC) members at the SwissTech Convention Centre, in Lausanne, Switzerland, July 11, 2017. [Photo/Xinhua]

Even without help from heads of state, LA 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 fulfil 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.

Garcetti and Hidalgo have long touted their good relations, and on Tuesday noted their cities' common positions on issues such as climate change and welcoming refugees.

Hidalgo cited her friendship with Garcetti as potentially a "key element" in the expected deal.