Scottish principals have warned that they may face the unpalatable choice of either cutting student numbers or allowing the quality of teaching and research to slip if a major funding gap between English and Scottish universities emerges.
Last week, the Scottish Liberal Democrats and Scottish Labour both declared their opposition to the introduction of upfront tuition fees or graduate contributions.
A parliamentary statement on the issue is expected this week from Mike Russell, the Scottish National Party education minister, which is also expected to rule out future student contributions.
Only the Scottish Conservative Party has committed to introducing fees as part of a "Scottish solution" to the funding problem.
Politicians across the other three main political parties have promised to plug any teaching funding gap between Scottish and English universities with public funds.
However, a rift has opened up over the size of the prospective gap, leaving principals concerned that future administrations may fail to provide sufficient public funds to fill it.
"Fundamentally we are looking at the moment at a position where three of the political parties are saying that the gap is much less than we believe. This means that the potential gap may not be met," said Ian Diamond, principal of the University of Aberdeen.
"We will end up with less money trying to do the same things. It's very difficult to see how one can maintain the number of students and the quality with less money."
Based on assumptions about the average tuition-fee rise in England and cuts to funding passed on from Westminster, the Scottish government forecasts a funding gap of £93 million a year from 2012-13.
But Professor Diamond said the assumptions failed to factor in future inflation to the tuition fee in England or a drop in demand for Scottish university education from prospective English students.
Scottish principals claim that the funding gap could be closer to £200 million a year, based on an average English tuition fee of £7,500 per year indexed to inflation.
Sir Tim O'Shea, acting convener of Universities Scotland and principal of the University of Edinburgh, called for "a sustainable and long-term solution to maintain accessibility, protect quality and ensure our universities remain a national asset".
Funding cuts are already causing problems across the Scottish sector. Strikes are planned at eight institutions this week, and relations between rank-and-file academics and senior management at the University of Glasgow are at a particularly low ebb.
Earlier this month, 200 Glasgow academics wrote to the Holyrood government to voice their concerns about the impact of cuts and departmental mergers.
"I've never known such despair and demoralisation," said one member of staff at the institution.
Professor Diamond indicated that some disruption was inevitable across the Scottish academy.
"We got £5.5 million less from the public purse last year than the year before. We have got to make those savings, and that's right across the sector," he said.
But the University and College Union Scotland - which was "de-recognised" for collective-bargaining arrangements by Robert Gordon University last week - said it believed that universities including Glasgow were using the funding cuts as an excuse to reform university structures and "get rid of staff that they don't really want".