Steve Edwards, executive director of South Yorkshire Passenger Transport Executive (SYPTE), said there is '˜evidence' Supertram provides '˜benefits to the whole region' despite only running across Sheffield and trial route into Rotherham.
The transport system expires in 2024 and reports seen by council leaders in South Yorkshire report the estimate renewal costs is to be '˜in excess of Â£200 million'.
Documents also show the renewal requires a '˜commitment to a local contribution' of around '˜20 per cent'.
But Doncaster Mayor Ros Jones has previously said any renewal should come from fares and central grants and not from taxpayers.
Proposals have been touted for a number of years to extend the service to other parts of South Yorkshire through the tram-train system. A two-year pilot scheme for tram-train running from Sheffield into Rotherham with a new station at Parkgate launches on Thursday - the first extension since 1993.
Asked what will happen if authorities like Doncaster and Barnsley refuse to put up their part of the cash, Mr Edwards said: 'That will go into discussion with the council leaders and Mayor Jarvis in terms of how we approach that. Our role is to present the information and the facts on benefits that tram brings not just Sheffield but the whole region.
'There is evidence that people from the whole region and also outside of the region make use of the tram system whether that's they work or they visit the area, they have park and ride sites associated with the tram network provide the facility that don't live in the centre of Sheffield.
'There is evidence that it supports and provides benefit to the whole region whether that's to employers or that's to residents. But ultimately that's a decision the leaders will have to take about how they move that forward.'