Markus Winkelhock says he expects to know on Monday if he will make his Formula One debut with Spyker at the European Grand Prix.
Spyker have a vacant seat after splitting with Christijan Albers following Silverstone.
Honda test driver Christian Klien is thought to be the favourite for the drive after testing with Spyker at Spa this week, but Winkelhock is still working to secure the seat - most likely as a one-off for the Nurburgring rather than for the remainder of 2007.
"It's difficult, I need the sponsor package to finish the season," Winkelhock told autosport.com.
"That's quite difficult. At the moment I'm still working for the German (European) GP, just to do the German race.
"It's not yet decided, but I think they will decide on Monday who will do the next race.
"I hope that if I get the possibility, I can then do well, but it is not easy to get the sponsors in the middle of the season.
"I just hope for a chance, and in the German (European) GP that would be perfect for me. For a German driver to have his first race in Germany would be cool."
Winkelhock, who is part of Spyker's test driver line-up, has returned to the DTM at Mugello this weekend to replace GP2-bound Adam Carroll, and intends to finish the season in the saloon series.
He acknowledged that swapping from DTM to F1 machinery would be difficult, but said that would not dissuade him if the opportunity arose.
"It's not easy if you jump from a DTM car to an F1 car and then back to a DTM, it's very different," Winkelhock said.
"They have different driving styles, so for sure it would not be easy to jump next week into a Formula One car but at the end of the day, I'm a racing driver, I want to drive all the time, and if I get the chance to drive in the German GP I have to do it."