The director of veterans affairs is empowered to contract with any veterans' organizations, now or hereafter chartered by act of congress to provide veterans services. All sums paid to veterans' organizations under contract shall be used by the organizations as specified in the contract in the maintenance of a rehabilitation service and to assist veterans in the prosecution of their claims and the solution of their problems arising out of military service. Such service and assistance shall be rendered all veterans and their dependents and also all beneficiaries of any military claim, and shall include but not be limited to those services now rendered by the service departments of the respective member organizations.