In order to prevent unnecessary expenses and duplications of functions, and to promote uniform and effective administration of relocation assistance programs for displaced persons under sections 4626, 4630, and 4635 of this title, a State agency may enter into contracts with any individual, firm, association, or corporation for services in connection with such programs, or may carry out its functions under this subchapter through any Federal or State governmental agency or instrumentality having an established organization for conducting relocation assistance programs. Such State agency shall, in carrying out the relocation assistance activities described in , whenever practicable, utilize the services of State or local housing agencies, or other agencies having experience in the administration or conduct of similar housing assistance activities.section 4626 of this title