Brazilian Grand Prix promoter Tamas Rohonyi is '99%' confident the race will stay at Interlagos, despite a mooted switch to a new Rio track for the 2021 Formula 1 season.
Sao Paulo's current contract runs out at the end of 2020 and the fate of the race after that date has not yet been decided.
F1 chiefs have been in discussions with representatives from a new track in Rio about switching the country's race there, with Brazilian president Jair Bolsonaro supporting that project and declaring earlier this year that it was "99%" likely to happen.
But Rohonyi is sceptical about the Rio plan and said his confidence in keeping the race at Interlagos was "the same percentage that the president mentioned".
He sees Interlagos as the only realistic option for a Brazilian GP.
"Either F1 remains here or there will be no Brazilian GP," Rohonyi told Autosport.
"I make no comments about Rio de Janeiro that I do not know, but what I do know is that there is a land with trees and animals, and so far there remains a land with trees and animals.
"I think it is physically impossible for an international event to happen there in 2021.
"But there are people who don't agree with that.
"Rio became an option because of the president's support, and Bolsonaro had Chase Carey by his side when he said F1 was 99% back in Rio de Janeiro.
"Today he wouldn't say that."
Rio previously hosted the Brazilian GP in 1978 (pictured below) and from 1981-89 but the Jacarepagua track used for those events has been demolished.
Rohonyi thinks Bolsonaro was misled when he said the new Rio Motorpark venue, which is planned to be built on army land, could be ready so soon.
"He was badly advised as there was no reason to say that," he said.
"For those who want to host an F1 GP in 2021, you would need to have the track ready in May of that year. It's late 2019, so you have 16 months for that. "
Rohonyi expects a decision about the future of the Brazilian GP to happen early next year - and he says he is seeking a long term deal that could run until 2030.
"For us, it's a very good period of contract," he added.
"It is increasingly difficult to work with short term contracts. Big companies do long-term planning.
"Heineken, for example, has its largest market is Brazil, and these guys do not work in terms of two or three years."
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