The following cooperative government contracts typically cover temporary staffing including:

staffing services
medical staffing
personnel services
virtual staffing services

Active Cooperative Contracts for Temporary Staffing

cooperative affiliation: NCPA active contract from Region 14 ESC, TX
Staffing Services and Related Solutions
cooperative affiliation: TIPS active contract from Region 8 ESC, TX
Staffing Services

Purchasing Cooperatives you can work with for Temporary Staffing

National Cooperative Purchasing Alliance (NCPA)

The Interlocal Purchasing System (TIPS)