If passed, the first branches would begin to close in April in the UK and 2027 in Ireland, with a gradual reduction over the coming decade.
Critics of the plans say the changes will decimate the Samaritans' work in local communities and have accused the charity's leadership of repeatedly ignoring requests to provide the rationale for the plans.
Some branches have called for a vote of no confidence in the chairman at a meeting next month.
More than 50 branches, over a quarter of the total, immediately raised concerns when the plans were unveiled and it seems that opposition has only grown.
The list of branches that would close has not been released, but James Watkins fears his one in Rhyl, Denbighshire, would go.
It's situated in the heart of the town, in one of the most deprived neighbourhoods in Britain, with high levels of mental health problems.
Mr Watkins, 58, says that volunteers are drawn to helping their own community as much as staffing the charity's nationwide phone line.
The branch's volunteers, he said, had recently been out at a local college and at the train station raising awareness of their presence.
"All of those things emanate from the fact we have a local branch and would likely go if we closed. Our branch has been going for over 50 years and our connections with our community has grown and grown," said Mr Watkins.
He's one of between 40 and 50 volunteers in Rhyl, but after speaking to colleagues said he was not aware that any of them would remain if the branch closed.
Last month, Mr Watkins organised a survey of volunteers across Wales. He says he received a response from 210 people, about one third of all Welsh volunteers.
Three quarters of people who responded said they would not move if their own branch was closed. The same proportion said they would not be interested in remote volunteering.
"With less people, [the Samaritans] are not going to be able to answer as many calls. This is the point we keep making and it seems to be falling on deaf ears. This could be the beginning of the end for the Samaritans."