Unison, the public-sector union, says compulsory redundancies among support staff are inevitable after New College Nottingham revealed its severe financial crisis.
The college, which has a deficit of almost pound;4.5 million, says most of the jobs will be lost through natural wastage and leaving existing vacancies unfilled.
Mike Scott, Unison's Nottingham branch organiser, said representatives were called to a meeting with senior college management at the end of May.
He said: "Basically, we were told that there was a major problem over finances and that a range of options were being considered.
"This has come out of nowhere, but it is clear that any decision will be taken without negotiation."
Mr Scott says the college plans to solve the cash crisis in two stages.
First, it will carry out a restructuring programme in which 25 full-time equivalent positions will be cut. As the college currently has 10 such vacancies, Mr Scott says at least 15 full jobs will be cut.
Second, there will then be what Mr Scott described as "a 10 per cent cut across the board affecting all sections of the college, including management". He says that 110 full-time equivalent jobs will be cut.
Currently there are only 40 vacancies, so 70 full-time staff will need to be made redundant.
He said: "Across both stages of the operation we expect between 85 and 100 redundancies.
"Obviously we are talking about full-time equivalent posts. Given that there are many job shares and part-time staff, the actual figure will be much higher."
A meeting of the local Unison branch has passed a motion of no confidence in the management, and says industrial action could take place unless the college rules out compulsory redundancies.
Although no teaching posts are said to be at risk at this stage, the lecturers' union Natfhe will hold talks with college management this week to discuss the situation.
Russ Escritt, Natfhe regional official, said: "We are being told that the lecturing staff are being protected and the restructuring is a means of changing the ratio of support staff to teaching staff.
"But we know the college is looking at what it says are expensive and inefficient areas, and our members are naturally worried.
"If you take away a layer of management and cut support staff, the work still has to be done and a large chunk of that could fall on our members'
In a statement, New College says the financial shortfall represents just 10 per cent of its total income. It denied that there will be any compulsory redundancies and said staff and unions are being consulted about the proposed changes, which will be in place by September 1. A spokeswoman said: "Some of the claims being made are a considerable exaggeration.
"We do not anticipate any compulsory redundancies. The net reduction in business support jobs is 88, of which 40-50 are existing vacancies that will not be filled. The rest we anticipate will be met by voluntary redundancies.
"This is a complex process and we are in a challenging period."
* Leicester college has scrapped plans to introduce new staff contracts which would have cut lecturers' holiday entitlement by eight days. FE Focus revealed last week (July 11) that the college had offered an "incentive" payment of pound;1,800 for those who accepted the cut from 48 days to 40.
But the move angered lecturers who voted unanimously for a stike ballot unless the contract, which had been due to come into effect from August 1, was withdrawn.