The project sponsor is the person that handles things that would normally be outside the project team's ability to handle. For example it could be a business executive that has direct control over company budgets to say how many people (resources) can be allocated to the project. Or, they could be the person that would need to work with another division within the company to get them to agree to an implementation date. There could be several decisions, costs, etc that the sponsor is a "champion" for the project that would be vital in keeping the project on time and on budget. Therefore, they are a direct influence on it's success or failure.
