"The polytechs will be controlled by a head office. They will 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.
"For high-performing polytechs like the Southern Institute of Technology, this will be devastating."
He also repeated his earlier claim - dismissed by Hipkins as scaremongering - that the reforms would lead to 1000 job losses.
He would not say who had leaked the paper to him, but it follows the leaking of a paper to National about the cannabis referendum last month - though the Government claimed that paper was out of date.
National has further claimed to have been leaked details about changes to Waikeria Prison, the Government's Budget priorities and legislative programme, the three strikes law, and the Government's goal to add 1800 extra police.
Hipkins said in a statement: "It appears National has got parts of a draft Cabinet paper, which was not due to go to Cabinet on Monday. We won't be making any comment until after Cabinet has made its decisions."
The paper leaked to Reti outlined the risks of the reforms, such as the uncertainty that could decrease participation and potentially affect the financial viability of some providers.
"Some decrease in education and training volumes is expected, particularly in shorter and lower-level work-based training and where current training that is not fit for purpose is phased out," the paper said.
Reti said National, if elected, would return all polytechnic assets to those institutions, and National would release a detailed education plan later this year.
The sector needed to change, but Reti said successful polytechnics should be allowed to continue.
"Why would we want to damage and break them? That's what would happen with these reforms. We will not damage or break those successful polytechnics."
The Cabinet paper reflected changes that Hipkins has previously flagged, such as the establishment of the New Zealand Institute of Skills and Technology, and transitioning polytechnics to become regional campuses of the new institute.
That transition would take two years, according to the paper.
It also proposed four to seven Workforce Development Councils (WDC) to have oversight of the sector and allow greater input from industry, and a single funding model to replace the current system of separate models for Industry Training Organisations (ITOs) and Institutes of Technology and Polytechnics (ITPs).
"ITOs and a number of employers currently involved in industry training strongly oppose shifting the role of supporting work-based learning to providers. But this shift is essential to create a new unified vocational education system to better meet the needs of learners and employers," the paper said.
It noted that not all ITPs supported having a single, centralised institute, and some local communities feared the loss of autonomy.
The leaked 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 the New Zealand Institute of Skills and Technology 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.
