The key stakeholder in the project was consulted before any major decisions were made.
Ключевой заинтересованный участник проекта был проконсультирован перед принятием любых важных решений.
Definitions
A key stakeholder is an individual or group that has a significant interest or investment in a project, organization, or decision-making process, and whose involvement is crucial for the success or failure of that initiative.