Politically important as well as personally satisfying was De Graeff's ties with his niece Wendela Bicker's husband Johan de Witt. De Witt eagerly sought De Graeff's advice and support and also enjoyed his clearness of mind and warm hospitality. Their relationship combined the closeness of family affection and the mutual respect of two strong minds as De Graeff was De Witt's equal as no one else was in Dutch politics at the time. In 1653 De Graeff made Johan de Witt a 'Grand Pensionary', a sort of chairman, of the States of Holland.