Ferrari president Sergio Marchionne says the threat that the Italian team could leave Formula One is a "serious" one.
Marchionne is unhappy with the sport's proposed 2021 engine rules, which were revealed at the end of October, and has said that Ferrari could leave F1.
He reiterated that message on Saturday at a news conference to launch the new partnership between Alfa Romeo and Sauber.
"The dialogue has started and will continue to evolve," Marchionne said. "We have time until 2020 to find a solution which benefits Ferrari. The threat of Ferrari leaving Formula One is serious. The agreement with Sauber expires in 2020-2021, right when Ferrari could leave.
"We have to find a solution which is good for the sport but we also have to be clear on the things we can't back down on."
Ferrari is the only team to have competed in every F1 season since its inauguration in 1950.
It is also the most successful team, with 16 constructors' championships and 15 drivers' titles.
However, the storied scuderia is now approaching a decade without a trophy, having last won the constructors' title in 2008, while its last individual champion was Kimi Raikkonen in 2007.
Mercedes has also complained about the proposed changes, which will make teams more equal in terms of engine power.