Esteban Gutierrez fears Sauber's budget is hindering their chances of finding a solution to a problem that has left them "stuck".
The Mexican racer and his new team-mate Adrian Sutil have yet to get off the mark this season, leaving Sauber as the only team aside from Caterham that has failed to score.
Hampered by an overweight car at the start of this season, Sauber have taken steps to lighten the load, however, even that did not yield the gains they had hoped.
And now Gutierrez fears they are "stuck".
"I think the explanation is pretty simple as we don't have enough downforce on the car and on the powertrain side, we cannot change things around because with the regulations we are not allowed to develop on the engine side," Gutierrez explained to Autosport.
"Also, on the car side, we are a team which does not have the budget of the big teams to change everything around.
"We are taking risks at the moment. We are exploring the car, taking different approaches, because at the moment we are stuck.
"It's probably not bringing the best consistency, but we need to keep searching."
But while sauber are searching, Gutierrez predicts a difficult season half of the season for the Swiss team.
"We cannot fall down into that fold because last year was pretty special.
"The tyres were changed in the middle of the season and we found something pretty unusual, and this year that is not really the case.
"We are not really far off expectations from the windtunnel, so there's not really something that's going to change the whole situation.
"We have to be truthful to ourselves and understand that we cannot just sit and hope that things are going to change.
"Last year we were pretty good in high-speed corners, so when we got to a track with high speed corners, we thought it could be a good opportunity for us.
"This year everywhere is quite weak [for our car].
"I have to say at the moment, it could not be worse."
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