Running a project: the "champion"

A project sponsor normally represents the people funding a project

A project champion is an informal role

has the vision to get the project going
pushes for a project to be accepted where there are competing priorities
keeps things going when difficulties arise

The project champion is often

a senior customer (user) who wants a particular capability; or
senior supplier (technician) who wants to try out the latest "toy"

Networking

Remember that the project manager isn't (normaly) the line manager of everyone on the team. The line managers may not even be working on the project. Building and maintaining good working relationships with the line managers will forestall problems later.