He spent considerable time reforming the PvdA 's internal organisation and public image , together with the party 's chairman Ruud Koole .
At that time Bos was the leader of the largest opposition party .
Bos spent considerable time reforming the PvdA 's internal organisation and public image , together with the party 's chairman Ruud Koole .
At that time Bos was the leader of the largest opposition party .