Mont. Code Ann. § 18-4-402

The department may participate in, sponsor, conduct, or administer a cooperative purchasing agreement for the procurement of any supplies or services with one or more public procurement units in accordance with an agreement entered into between the participants independent of the requirements of part 3. Cooperative purchasing may include purchasing through federal supply schedules of the United States general services administration, joint or multiparty contracts between public procurement units, open-ended state public procurement unit contracts that are made available to local public procurement units, and competitive contracts established by for-profit, not-for-profit, or nonprofit cooperative entities.