Mr Goff said Mr Key has had three years of photo opportunities and a "marvellous spin machine" to foster his popular public image.
"This election is not about New Zealand's Next Top Model. This election is about serious decisions that we need to make for the future of our country."
Despite most polls having the Labour Party around 20 percentage points behind the National Party, Mr Goff said the party should not be written off.
"We've got a long way to go," he admitted.
"Labour has got serious policy we're putting before the people. We are saying, 'look, we are going to be honest with New Zealand, they are some real difficulties in the economy.
Debt is out of control ... we've been downgraded for the first time in 13 years. Labour has a serious plan to deal with that debt. We've got to get that debt down."
Mr Goff said the party's policies were fully costed and affordable.
"We will pay down our debt as quickly as National will, but the difference is we will still have the assets producing the hundreds of millions dollars in dividends at the end of that, because we will be using a fair capital gains tax to meet the cost of repaying that debt."
Mr Goff believed National would sell off state assets to pay for further projects, despite the Prime Minister saying the Government would retain a majority share.
"The difference between Mr Key and I, is I will say what the hard facts are before the election and what Labour is going to do, not change my mind after the election like Mr Key did on GST, on cutting KiwiSaver, on cutting Working For Families, on slashing not capping the public service, all of those were broken promises."
The Labour leader also accused the Prime Minister of lying over claims the Labour Party would need to borrow more to pay for their election promises.
John Key told Newstalk ZB this morning that while National's partial asset sales would pay for their proposed $5 billion to $7 billion "Future Investment Fund", Labour will need to borrow more.
"That's the issue with Labour. They are on track now to borrow $17 billion more over the first four years if they become the Government.
"When they went out there last week and said to you they are going to raise the age of the pension from 65 to 67, they weren't being brave or bold, what they were trying to do was play catch up for all the debts and spending promises they've made."
However Mr Goff dismissed Mr Key's claim as a lie.
"There is as much truth to that comment as there was when John Key got up in the House and claimed that Standard and Poors had said they would downgrade New Zealand if Labour was elected," he told Radio New Zealand.
"That was a lie and this is a lie. There is absolutely no truth in that at all."
- Herald Online staff
