Glasgow University's Association of University Teachers has broken ranks with the other campus unions, refusing to endorse a voluntary severance scheme that is part of the university's £10 million savings plan.
The university, which wants to shed 250 posts, this week admitted that academics are proving slower than other staff to investigate the scheme, which closes in mid-September.
The other campus unions - Amicus, Unison, the GMB and TGWU - have agreed that the scheme is the best that could be achieved at present, and that staff should consider it.
But Tony Axon, a spokesperson for AUT Scotland, said: "(We) accept that there are financial problems at Glasgow University, and we are working with the university to ascertain the depth of these problems.
"We therefore reserve our position on the financial state until we have fully considered the figures and the savings that could be met through means other than redundancies." Dr Axon said the union would oppose any compulsory job losses.
A university spokesperson said: "Since the original letter offering voluntary severance was issued 21 days ago, there have been up to 200 expressions of interest from both academic and support staff."
Individuals' suitability for the scheme would be based on the university's long-term focus.
"It is fair to say that academic staff will be slower to come forward to opt for the scheme," the spokesperson said.
"Reasons could include the logistics of finding similar work at another institution or the need to complete specific research projects, thus making it a lengthier process."