As a result of deregulation, up to a third of services in the region could be axed because private bus companies don't consider them profitable enough.
Documents from Barnsley and Doncaster councils reveal concerns over costs and timescales for bus franchising, which campaigners say could stifle service improvement.
New data from the Department for Transport shows the region is falling behind on public transport improvements – as Sheffield Council urges the next Mayor to look at greater public control.
After years of decline, Andy Burnham is bringing Manchester's buses back under public control. Now campaigners are calling on Dan Jarvis to do the same.