A total of 29 charities, including Action for Children and Contact a Family, have joined together to create the Disabled Children Partnership, amid fears that disabled children's issues have slipped down the government's agenda.
The group said this month's Spring Budget, which featured a £2bn investment in adult social care, but no funding boost for disabled children, shows that improving support has slipped off the political agenda. National Children's Bureau figures show that funding for disabled children's services was cut by £3.2bn between 2010 and 2015.
The group has said it intends to launch a major campaign in the summer ahead of the government's next Budget, in which it wants additional funding for disabled children's services.
Amanda Batten, chief executive of Contact a Family and chair of the partnership, said: "We never hear the Prime Minister talk about disabled children in any of her speeches.
"Disabled children as a whole weren't mentioned in the Budget so we feel that disabled children and their families don't really feature in the Prime Minister's reform agenda."
Respite care, short breaks, specialist equipment in the home, family support and projects that tackle isolation among disabled children and their families, are among the services the group wants to see better funded.
"Ultimately we are calling on government to address the current and growing gaps in services and that means more funding," Batten said.
"Children's social care budgets have been declining and the vast majority of disabled children live at home with their families and we want to see investment in the sorts of services that support them."
This summer's promotional push is also aimed at raising awareness of "the realities of the lives of disabled children and their families", said Batten, who cited 2014 research by partnership member Scope that found 43 per cent of British people did not know anyone who is disabled.
A survey by Contact a Family in 2015 found that 69 per cent of families of disabled children did not receive any support outside of family and friends.
A Department for Education spokesman said: "The UK is already a world leader in disability rights, and we spend £50bn a year to support disabled people. But we know more must be done - we want to make sure families with disabled children feel fully supported, and that their child has the best possible quality of care, so we are giving councils almost £200bn to spend on local services by 2020."
The full list of charities is:
- Action for Children
- Contact a Family
- Council for Disabled Children/National Children's Bureau
- Family Fund
- Royal Mencap Society
- National Autistic Society
- The Children's Trust
- Together for Short Lives
- Ambitious About Autism
- Guide Dogs
- Credo Care
- Carers Trust
- Carers UK
- Child Poverty Action Group
- The Communications Trust
- Family and Childcare Trust
- I CAN
- National Deaf Children's Society
- Rainbow Trust Children's Charity
- Whizz Kidz
- Working Families
- CLIC Sargent
- SeaShell Trust