Two mothers, Fiona Porter and Sue O'Reilly are asking voters through their web-based Mad as Hell campaign to take a pledge only to support parties in federal and state elections that commit to a national disability insurance scheme. As well, they want a promise that those with a disability and their families will be the ones to decide how best to use funding to meet individual needs.

Their aim is to lift an issue that often is ignored into prominence.

Ms O'Reilly, who has a son with cerebral palsy, said: When Kevin Rudd and Tony Abbott launch their election campaigns, we would like to hear them say that, if elected, they would radically overhaul the Third World disability support system in the next term of government.

Given there are an estimated 1.5 million people with a severe disability -- ranging from autism to cerebral palsy to brain damage or quadriplegia caused by personal accidents -- as well as their families, outside carers and disability support workers, Ms Porter and Ms O'Reilly say their campaign could influence the votes of two million to three million Australians whose lives are affected directly by disability.

Parliamentary Secretary for Disabilities Bill Shorten acknowledges the political potency of the issue. I have a view that disability is as big an issue as climate change in the electorate, Mr Shorten told The Weekend Australian. It is the greatest political sleeper issue in Australia. I think that politicians need to wake up to the size of the disability vote.

He says the government will decide at senior levels how to respond specifically to the campaign pledge. Mr Shorten supports a national disability insurance scheme, calling it a once-in-a-generation chance to put support for disability on a secure footing and argues that it will save money in the long run through early intervention and putting more people into work.

The government has asked the Productivity Commission to report by the middle of next year on the feasibility of the scheme and alternatives for long-time care and support.

The opposition has supported the reference to the Productivity Commission. Opposition disabilities spokesman Mitch Fifield would not say how the Coalition would respond to the pledge, but added: It is always a good thing for political parties to be put under pressure.