New Zealand First leader Winston Peters is disputing Labour's costing of its universal student allowance policy.
Labour leader Helen Clark announced on Monday that the party would phase out parental income testing on student allowances, abolishing income testing by 2012.
The policy has been costed at $210 million a year when fully implementated.
Addressing students at Waikato University on Tuesday, Mr Peters said Labour's costing cannot be accurate, and he believed the actual cost would be $728 million.
He reaffirmed his party's policy of bringing in a universal student allowance.
Peters speaks about SFO investigation
During his speech Mr Peters also spoke of how he felt about accusations over donations to him and his party.
The Serious Fraud Office on 10 October cleared New Zealand First of any allegations of fraud relating to donations channelled through the Spencer Trust.
The SFO passed on information to the ongoing police and Electoral Commission investigations into the party's 2005 and 2007 returns.
Winston Peters told the audience what it was like for him during the investigation.
"You know what its like to walk through an airport with people whispering 'that guy's a crook', you know what its like? Well I do."
Mr Peters attacked ACT and National, saying they thought they could fire him, bring the Government down, have a snap election and they would be "home and hosed".
"And the first week of the campaign started, and they can't even get out of the blocks.
"Now those of you who voted National, I can forgive you, you're young," he said.
He ended his speech telling the students to vote for their Grandmas this election, which prompted loud laughter from the audience.