"A National Party that makes a decision that it's going to sell assets when 80 per cent of New Zealanders are against it can't be described in any other way," he later told reporters.
"It's arrogant, it's disregarding what most New Zealanders believe."
Mr Goff said during the final leaders' debate on Wednesday evening that Mr Key had been unable to give voters an assurance that shares in Meridian Energy, Mighty River Power, Genesis Energy and Solid Energy would not eventually end up in the hands of foreign investors.
Starting in Rotorua, Mr Goff and his candidates will today take a bus tour to bring their message to voters and supporters in the towns and along the Waikato River where many of the hydroelectric power stations owned and operated by the state-owned power companies lie.
He will campaign until midnight in order to swing as many as possible of the large number of undecided voters he needs to bridge the massive gap between Labour and National in the polls.
Yesterday he told the Herald the asset sales issue was the key.
"If we do well it will be about that."
He said Mr Key had shown he was uncomfortable talking about the policy and had relied on distractions such as the Rugby World Cup, and more recently the teapot tape to divert public attention.
The less New Zealanders thought about the issues the more the National Party was pleased during the campaign.
"I don't want New Zealanders to wake up with a hangover on Sunday morning thinking, 'My God, we're about to sell our future."'