Nico Hulkenberg on Thursday said he turned down a chance to drive for Lotus in the final two races of 2013 because it was too risky.
The 26-year-old German was offered the opportunity to replace Ferrari-bound Kimi Raikkonen.
But Hulkenberg, who drives for Sauber, said that although it looked good from one perspective, it was also very risky when looked at in a wider context.
"Of course it was attractive," he said. "It sounded attractive from the outside, but it's for the last two races, which brings also some risk with it.
"You have to see the bigger picture beyond those two races, and see what can happen then. And that's why we came up with his decision.
"Stepping into a new car which you don't know. If I had stepped in, I don't think people would have expected me to beat Romain [Grosjean] right away.
"He's delivering very good results -- so it was from that point of view that I had to decide."
Lotus has signed another Finn Heikki Kovalainen to race in Austin and Sao Paulo.
Hulkenberg, however, admitted, he did visit Lotus to talk about a deal for 2014.
Kovalainen's deal came after efforts to recruit former world champion Michael Schumacher, now in retirement, came to nothing.
Schumacher's manager Sabine Kehm told German newspaper Bild: "There have been quite a few requests in the past. Michael would still be fit enough, but he has a new life. I don't find it unusual that people ask.
"Many people changed their assessment about Michael because of Nico Rosberg's recent performances compared to those of Lewis Hamilton.
"Michael drove as well as Nico, just as Nico is driving as well as Lewis."