Thousands of vulnerable people in Brighton, Hove and East Sussex are at risk from cuts in housing budgets.
The National Housing Federation, which calculated that 5,320 people would lose out, said that the danger was greater because the support was often discretionary.
This type of spending is more likely to be cut than spending on statutory services – those which councils must provide.
The federation is now holding more than a hundred events across the South East as part of South East Supported Housing Month which runs until Friday 10 December.
It said: “It is giving key decision makers, such as councillors and MPs, an opportunity to find out more about how housing associations and other providers are helping vulnerable people live independent lives.
“Providers are inviting them to open days and exhibitions, as well as arts trails, coffee mornings, film screenings and healthy living sessions, to give them a chance to get stuck in and meet some of the service users.
“There are a huge range of services at risk in the South East, including services for people with learning disabilities and mental health problems, foyers for young people, homeless hostels and other temporary accommodation, refuges from domestic violence and sheltered and extra care housing for older people.”
The federation is also warning that cuts to the Supporting People programme could potentially lead to an increase in crime.
The concern revolves around the closure of hostels for ex-offenders and a reduction in the number of ex-offender support workers.
More than 270 former prisoners across the region would have less supervision and support to help them reintegrate into society and therefore be at a greater risk of re-offending.
Other vulnerable groups who are likely to lose out include older people with support needs, people with mental health problems and learning disabilities, the blind, the deaf and the physically disabled.
A national evaluation has estimated that the £1.6 billion spent each year on housing-related support through the Supporting People programme generates savings of £3.4 billion to the public purse.
It found that by intervening earlier to prevent more severe problems arising, people were helped to live more independently, avoiding more costly acute services.
The federation said that preventative support through housing associations led to better outcomes for service-users and their families.
It said budget savings were made in the health and social services sectors through the avoidance of hospital admissions and reduced numbers of children being taken into care.
Warren Finney, South East regional manager for the National Housing Federation, said: “South East Supported Housing Month is all about inspiring councillors and other key stakeholders to get a better understanding of the importance of these services.
“It’s particularly vital as they’ll be making crucial decisions about the future of them over the coming months.
“Not only do these services make a huge difference to over 136,000 people in the South East, but evidence has clearly shown that they save the taxpayer billions of pounds through the avoidance of costly hospital admissions and recourse to other services.
“If the Supporting People budget is substantially cut here, thousands of vulnerable people will end up losing the support they depend on, meaning they will no longer be able to lead self-sufficient lives and will increasingly have to rely on acute health and other services.
“We hope that South East Supported Housing Month will help to raise awareness of that fact.”