Ralf Schumacher is to quit Toyota at the end of the season after three years with the Japanese team, but has not confirmed which team he will move to.
Schumacher has failed to register a podium finish with Toyota
Schumacher's future has been the source of speculation following a torrid season in which the 32-year-old has taken five points in 15 Grands Prix.
"I have opted to look for a new challenge," he told his website.
"I'm going to have conversations in the coming weeks, and I will announce my decision when the season is over."
Schumacher is on course for his lowest points tally since joining Formula One in 1997. In each of his two previous seasons at Toyota he has amassed 20 points.
It is a far cry from his time at Williams, where he recorded six Grand Prix wins between 2001 and 2003 and was touted to follow in the footsteps of his world champion brother, Michael.
Schumacher added: "The financial aspect is far less important than the chance of being involved in the development of a car and being successful afterwards.
"On the one hand, I regarded it as a major and exciting challenge to be involved in the development of a new racing car.
"On the other hand, I also learned to like the Japanese style of living during my long stay in Japan before entering Formula One, and I still get on well with the Japanese mentality.
"But I have been waiting for years for a competitive car.
"Toyota was still a nice and interesting experience - particularly the co-operation with the team, engineers and mechanics, but it's time now to look for a new challenge."