The group, which was set up more than five years ago by TV presenter Dame Esther Rantzen, 78, said it is struggling to compete for donations with other more high profile charities.
It said the move would save up to £500,000 a year.
The under-threat staff, who take more than 10,000 calls a week from lonely vulnerable pensioners at their call centre in Amy Johnson Way, South Shore, will now take part in a “meaningful consultation” to determine their fate.
Sophie Andrews, the charity’s chief executive, said Silver Line would have to adapt to cope with the rising demand of taking more than two million calls in the past five years.
She said: “Initially set up to meet the perceived need for a helpline specifically catering to lonely older people, it was impossible at the outset for the organisation to predict the sheer volume of demand there would be for such a service.
“As a result of this huge demand two things have become clear, both that this service is essential, and that we need to adapt as an organisation in order to continue to meet the rising demand for the service in a sustainable and cost-effective way.
“That realisation has led us to review the way we currently operate, and as a result, the organisation is proposing a change to its model from a helpline staffed entirely by paid employees, to one which is shared between paid staff and volunteers.
“The organisation will now enter a meaningful consultation process with affected staff to determine how to proceed with the proposal in order to make The Silver Line more stable and resilient in future, and most importantly enable us to continue providing this important service for older people.”
“Due to the nature of this sort of process nothing can be set in stone until everyone affected has been given the chance to take part in a meaningful consultation lasting at least 30 days. We are now only at the beginning of this process.”
Ms Andrew says the staff at the Helpline have been made aware that their jobs are at risk.
She added: “All helpline advisors are involved in the consultation process which equates to around 100 employees. The proposal is to close the daytime shift and to meet demand during the day using volunteers.
“However, as it is still a consultation period we cannot make predictions on the number of redundancies as we can’t account yet for people potentially taking on different shifts, moving into other roles within the organisation or finding other solutions throughout the consultation.
“Based on the proposal, we project we could potentially save up to £500,000 per year if the proposal were to be accepted.”
The donation crisis was highlighted by Esther Rantzen in December.
She said that last Christmas the charity was unable to take 5,000 calls due to having insufficient resources to meet demand.
She added: “The top charities are those working with dogs and cancer patients. I like dogs and I care about cancer, but it would be nice if there was an older persons’ charity in the top 20 in Great Britain.
“We are here in Blackpool, we are local to you, we are your charity, we urgently need resources, we need funds if you go to our website will see how easy it is to give. More and more people need us. Last Christmas we were not able to keep up with the demand.”
Silver Line is a free, national and confidential helpline for lonely older people which is open 24 hours a day, 365 days per year. The charity was founded by Dame Esther in November 2013, and was inspired by the loneliness she experienced after the death of her husband, the BBC producer Desmond Wilcox.
The Duchess of Cornwall is a patron of the charity and visited the Blackpool office in 2017.
According to the charity’s latest set of accounts, the helpline took 257,884 calls in its first year, 373,778 in its second, 487,826 in its third, 498,980 in its fourth, and 534,752 up to October last year – its fifth.
Income was £4,699,963, down from £5,126,370 in 2017, and spending was £4,487,782, down from £4,686,125.
HOW TO DONATE
Call: 0207 2242020Online: www.thesilverline.org.uk/donateText: Text SILVER to 70660 to donate £10Cheque: Send a cheque payable to The Silver Line to Trade Tower, Calico Row, London SW11 3YH.