Felipe Massa has admitted he could drive off the grid altogether if Ferrari does not extend his contract beyond 2013.
The well-connected Brazilian newspaper O Estado de S.Paulo newspaper said Nico Hulkenberg and Paul di Resta are at the front of the queue if Ferrari decide Massa's struggle for results recently should end his long tenure.
Both candidates were not denying the speculation in Hungary.
"To tell you the truth," Force India's di Resta told F1's official website, "my management team is looking at what is best for me to move forward."
And Sauber's Hulkenberg is quoted by Frankfurter Rundschau: "Ferrari has a tremendous history and is one of the top teams.
"But as to my future, that's still wide open."
Massa, 32, admitted he needs to put his focus on the road in front of him.
"You can't drive with extra worry or fear," he told Brazilian correspondent Livio Oricchio. "I've never done that in my life.
"If I am forced to change, it would have to be somewhere else competitive, otherwise I wouldn't want to stay in Formula One," Massa insisted.
Globo quotes Massa adding: "I want to stay in F1, but to compete, not to (just) participate.
"If for some reason I do not have the chance to stay at Ferrari, I will try to go somewhere else.
"But if I can only go to small teams, I'm not interested," he insisted.