Cardiff social care staff could strike over council plans to reorganise day care services for people with learning difficulties.
Unison officials say more than 50 care staff will be asked to reapply for fewer posts. Staff will also be required to work shifts between 7am and 11pm, seven days a week, making it more difficult for workers with families.
The union said an emergency meeting next week could lead to calls for industrial action.
Unison Cardiff social work officer Mark Turner said: "All the staff are having their contracts ripped up and asked to apply for a fewer number of jobs. The council is saying it will try and redeploy people who lose their jobs elsewhere in the service but that could be doing anything."
Turner said the plan would represent a "gradual withdrawal of service from professional staff" because it also suggested that service users should receive more care from friends, family and volunteers, and rely less on formal care.
However, the number of day care centres for 230 Cardiff service users will increase from five to six and more emphasis will be placed on person-centred development through participation in community projects.
A council spokesperson said it would scrap a tier of management under the plans, but they would be cost-neutral and were "unlikely" to lead to job losses.