Most projects cross departmental or enterprise lines of authority, and many projects get funding from more than one source. We all should know that projects are temporary endeavors undertaken to create a unique product, service, or result. It is the temporary nature and uniqueness of projects that make the job of the project manager so difficult. Project managers must work with different groups of people (stakeholders) to meet project objectives, and usually don't have any much authority to get stakeholders to perform the project work. A strong project sponsor can help the project manager address the people issues (and many more project issues that will arise).
A project sponsor's role is to help make project decisions (formal authority), and he or she is ultimately responsible for the project's success. The sponsor comes from the executive or senior management ranks (depending on the size of the project) and should be influential, a respected politician, and have a track record for getting things done. You don't want a "Political Shark" for a sponsor.
The sponsors authority and stature should be such that they are independent as much as possible of the project's goals and objectives so they can cut through the political landscape to get critical project decisions made.
Sponsors don't just support projects; they support the project manager and project team. They are the project champion and won't allow others to sabotage the project manager, the project team, or the project's goals. They have authority that comes from their title and position within the organization. In order for sponsors to be effective they must have organizational respect, proven leadership qualities, and be honest in their dealings. As mentioned before, they aren't political sharks, they are adept at rallying the troops (project team and stakeholders), presenting a clear message, and are supportive of the project manager.
Ideal Sponsor Responsibilities
Writes the Project Charter
Help to define project team roles and responsibilities
Acts as an advisor to the project manager
Has control of project funding
Reviews and Approves any Statements of Work/Contracts and Planning Documents
Bad Sponsor Characteristics
Always too busy to meet with the project manager and project team
Doesn't have time to write a project charter
Won't get involved in assigning project roles and responsibilities
Doesn't have time to approve documents, or delegates all sponsor responsibility to others.
Blames others when things go wrong, and/or won't work to resolve project issues
Always takes credit for any project success
Is surprised when the project's deliverables aren't what they expected
A bad sponsor is a project manager's worst nightmare. Avoid them at all costs if possible.