Del. Code tit. 29, § 5918

The rules shall provide for promotions, giving consideration to the applicant’s qualifications, performance record, seniority, conduct and, where practicable, to the results of competitive recruitment. Vacancies shall be filled by promotion whenever practicable and in the best interest of the classified service. Any promotional competition for a position funded solely by general funded appropriations, involving 2 or more candidates and a referral list issued by the Secretary, shall be considered a competitive recruitment under § 5917 of this title.