Poll after poll has indicated a majority of New Zealanders oppose the plan - most recently a Massey University survey that found 75.9 per cent of voters were against it.
Waikato University sociologist Kellie McNeil said Mr Key's personal appeal was a major factor.
"He's been touted as New Zealand's celebrity Prime Minister and I think that certainly has worked for him in terms of capturing the public's attention. He does have some problems with the public's perception of how trustworthy he is but I think that charismatic ... persona perhaps overcomes some of the doubts people might have about his trustworthiness."
Dr McNeill said voters would also be swayed by other factors.
"They're perhaps prepared to forgo having an opinion on assets sales and support National's other policies particularly around things like welfare reform and tougher sentencing, some of those traditional areas for National."
Victoria University political scientist Jon Johansson said voters' decisions were influenced by many factors, "and favourable reasons for supporting this Government trump their unease about this ... policy".
Dr Johansson said under "normal" conditions National would have been more thoroughly scrutinised and may have been at risk because of the policy but, given Mr Key had handled well the Canterbury earthquakes, the Pike River disaster and the global financial problems, "people have suspended disbelief about the actual competence and quality of this Government and its performance".
Meanwhile, Mr Key this week tacitly acknowledged voters have yet to be convinced of the policy's merit.
Asked whether he believed New Zealanders supported the policy Mr Key said: "they might once they have an opportunity to see how that works".
But Dr Johansson said National was running the risk the policy would backfire on them when it executed the asset sales.
In spite of the policy's unpopularity in the polls, National could legitimately claim a mandate for it if they won the election on Saturday, he said.
"But having claimed that mandate, when they carry on and actually institute that policy they may then suffer a poll reversal because when the pollsters ring up people after you've had a week's headlines about the first of the mixed ownership sales, that's when people are going to react to it."
On the other hand, the policy itself was a valuable asset to the Labour opposition. Labour's focus on the policy could prevent them from suffering the same humiliation inflicted on National in 2002 where it slumped to near 20 per cent at the polling booth.
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