National tertiary education spokesman Shane Reti released details of the paper yesterday, saying it was due to be presented on Monday.
Dr Reti said under the new model, polytechnics would be controlled by a head office.
The Cabinet paper reflected changes Education Minister Chris Hipkins had previously flagged, such as the establishment of the New Zealand Institute of Skills and Technology, and turning polytechnics into regional campuses of the new institute.
Mr Hipkins said yesterday National appeared to have obtained parts of a draft that was never going to be presented next week.
"We won't be making any comment until after Cabinet has made its decisions," Mr Hipkins said.
Mr Ker said the minister's response was not enough.
"It is so unsettling for our staff that it is unimaginable," Mr Ker said.
"It is unfortunate communications like this get leaked.
"The whole sector now wants Minister Hipkins to come out and firmly deny that this is the direction of travel or to confirm it."
Dr Reti said polytechnics would "have their cash and community legacy assets ring-fenced at head office".
"All other assets, including buildings and land, will be taken away and consolidated," Dr Reti said.
The leaked document model also outlined introducing four to seven workforce development councils (WDCs) to have oversight of the sector and allow greater input from industry.
The Government has said the outcome of consultation on the sector reforms will be announced in July.
Mr Ker hoped Mr Hipkins would clarify the situation next week.
"[Otherwise] it's another five weeks of quite enormous uncertainty.
"I guess that that uncertainty will [be felt] in the international market."
Mr Ker has advocated passionately for an alternative model, whereby polytechnics retained more individual autonomy, an idea widely supported by the Dunedin community.
Polytechnics would retain their own character, culture and branding.
Southern Institute of Technology chief executive Penny Simmons said she was "alarmed" by the draft.
Consultation had gone on for 18 months now, and she still hoped it had been undertaken genuinely.
Six of the 16 polytechnics and institutes - Otago Polytechnic, Southern Institute of Technology, Ara, Eastern Institute of Technology, the Open Polytechnic and Ucol - reported surpluses last year.
According to the leaked paper, the switch from the current model to the new one would take two years.
The paper did not include any financial details of the overhaul, saying only there were "significant costs and risks to manage" but the risks of doing nothing were "more significant".
The paper's timeline had the establishment of the skills and technology institute by April next year, WDCs in the 2020-21 year, a single funding model from 2021, and the phased transition by the end of 2022-23.
Dunedin National Party list MP Michael Woodhouse said the proposal would be detrimental to the region's brand, which was globally recognised.
"This is disastrous for regional education and apprenticeships," he said.
"The Government's `we know best' attitude will mean the organising of apprentices will be taken from industry, who know the needs of Otago best, and instead will be given to one polytech."
Otago Polytechnic was one of the highest performing polytechnics in the country "with a reputation for being nimble to the needs of its community".
"The loss of autonomy signalled by this change could be very bad for the region."