Australia’s next federal government faces a growing push to expand National Disability Insurance Scheme coverage to people aged over 65, adding billions of dollars to its already ballooning cost.

Crossbench MPs including Rebekha Sharkie, Zali Steggall, Andrew Wilkie and Helen Haines have signed on to a plan to allow senior Australians cover under the $30 billion scheme, with Senate support locked in from the Greens and Rex Patrick.