Acts as the primary liaison between vendors, contractors, County departments, local and State agencies, and the public regarding purchasing/contracting matters; directs research pertaining to market conditions and new products; works with vendors to develop new sources of supply; negotiates and evaluates prices, discounts, delivery conditions, products and services offered by a variety of vendors; maintains an active bid list by commodity; maintains lists of emergency resources. Monitors and evaluates the performance of vendors to ensure that all parties are complying with contractual terms; maintains cooperative and positive relationships with sources of supply; stays informed regarding price trends, availability of supplies, new items, and product reliability; investigates and resolves complaints from departments and vendors about products, services and issues regarding bid protests and contract awards; meets with vendors and department staff to plan special projects, arrange for work completion and/or resolve problems.