The Act Party had been announcing its proposal for a national cancer centre, receiving a positive response at the event.
Act list candidate Paul Henry publicly raised the idea as an off-the-cuff remark and said he expected to be chastised.
But he told the crowd at the launch the party has now adopted the policy, and will build the $2 billion centre if re-elected in November.
Henry said the centre would have two major campuses – one in Auckland and one in Christchurch. He said the project would be funded by public-private partnership financing, donations, existing Crown health investment and private capital.