Klien still hoping for 2010 F1 seat

At present the only teams that still have vacancies for 2010 are Campos and US F1.

"As long as there are cockpits available I will try hard," Klien said.

"I came close at Sauber and at Renault. At both teams I was in the running until the day before announcements of de la Rosa and Petrov respectively.

"Over the winter there were changes in the teams' leading personnel and in team structures that were not foreseeable for me and that did not play into my hands."

Klien, who turned 27 today, raced in 46 grands prix for Jaguar and Red Bull between 2004 and 2006 before becoming a reserve driver for Honda and BMW Sauber. He is willing to consider another third driver role as a fall-back option, although the opportunities for this position are also limited.

He and father-manager Johannes Klien said there was no 'plan c' at present because they had concentrated all their efforts on F1. Klien, who was a member of the Peugeot works sportscar team in 2008 and 2009, said he had ruled out a return to the Le Mans 24 Hours this year because it clashes with the Canadian GP and "we were focused on securing an F1 seat."