The National Party has launched a petition calling on the government to save Otago Polytechnic.
The petition is in response to a government proposal to amalgamate every polytechnic in New Zealand and manage them centrally.
Dunedin-based National MP Michael Woodhouse said it would mean a loss not only of identity but also of the nimbleness and adaptability for Otago Polytechnic.
"The Otago brand is globally recognised. Graduates can take their qualifications anywhere in the world, particularly in the health sector. Losing that brand identity will make studying at whatever Otago Polytechnic's replacement is much less attractive," he said.
The new polytechnic council would be made up primarily of political appointees, so a local voice could be lost, Mr Woodhouse said.
"Our hard-earned cash reserves will be hoovered up by Wellington-based bureaucrats to fund the eye-watering cost of these unnecessary reforms."
Mr Woodhouse said the polytechnic was a world-class institution renowned for its high-quality teaching and courses, but would be destroyed by the creation of a megapolytechnic.
If elected in 2020, National would return polytechnic assets taken by the current government and give them back to communities, Mr Woodhouse said.
The government plans to spend $200 million overhauling vocational education by creating the biggest tertiary institution in the country - a national polytechnic with more than 130,000 students.
The New Zealand Institute of Skills and Technology would be created in April 2020 by making the existing 16 polytechnics and institutes of technology into subsidiaries of a national institute.
Education Minister Chris Hipkins said the changes were needed because too many polytechnics were making deficits, too few people were in training, and vocational education was too complex.
"If you want to train to be a truck driver right now there are 19 different qualifications you could do," he said.
"If you get into the primary industries - agriculture, horticulture - it's pages and pages and pages of qualifications and programmes that are often delivering the same outcome."
A national system would deliver fewer courses, but overall offer a wider range of options in a more systematic way, he said.
The national institute would take over responsibility for on-the-job training and apprenticeships over the next two to three years.
The current 11 industry training organisations would be replaced by Workforce Development Councils that would have the power to veto vocational courses that did not meet industry requirements.
Business NZ chief executive Kirk Hope said not all courses at polytechnics were currently fit for purpose to meet employers' needs.
"From an industry perspective and from a learner perspective ... the system had been pretty fragmented," Mr Hope said.
Most polytechnics support the move to amalgamate.
One of the largest, Manukau Institute of Technology, said South Auckland students would benefit from the creation of a national polytechnic and a streamlined apprenticeship system.
John Snook, chief executive of one of the smallest, the Western Institute of Technology in Taranaki, said he was not worried that small institutes would be sidelined.
"I think they get the best of both worlds here. They get some regional intervention to make sure we're aligned with the economic development plan of the region and they also get the support of a central agency that is big enough and has the scale to provide quality programmes and learning material that we all need."
Nelson Marlborough Institute of Technology said it was mostly supportive of the changes and Ara Institute of Canterbury said the announcement held "a number of positives".
However, Southern Institute of Technology chief executive Penny Simmonds was concerned the polytech could lose autonomy through the merger.
Carla Forbes of the group Stand up for SIT said there were widespread fears the merger would kill off the successes of the Southland region.
She said Southland Institute of Technology was one of the key economic drivers for Southland, so a merger would have negative downstream effects on businesses and the community.