The controversy over taped Bill English and Lockwood Smith conversations could sway swing voters, says a political studies academic.
University of Auckland senior lecturer Dr Joe Atkinson said the electorate is "volatile" and could be influenced by the recorded conversations.
"Swing voters are often quite naive about this sort of thing. Ordinary people want their politicians to be straight forwardly candid and honest and they're always shocked when they hear that they're not and the media encourages them to be shocked about that," Dr Atkinson said.
He said some naive voters may trust John Key less.
"This gives Labour more ammunition for their: slippery Key can you trust National line that they ran at the last election," he said.
Dr Atkinson said the story has been covered by the media partly because National has not released any detailed policy.
"In a funny kind of way, National opens itself to this kind of salacious political talk precisely because it has been vague about policy in the same way that Winston Peters is getting heavy metal from the media because he's being vague about what happened," Dr Atkinson said.
He said National seems to have decided not to release policy until the election campaign and will "have to take this nasty stuff" until the campaign-proper begins.
"The problem with that kind of strategy is that they might find the polls have changed direction and that they've left it too late," Dr Atkinson said.
He said the broadcasting of secretly recorded conversations will not stop politicians from talking to their constituents but they may "choose their words more carefully".
"What is new is that there is taped evidence of politician playing this complicated game but it is politics as usual," Dr Atkinson said.