Key Points:

Helen Clark laid into National leader John Key's performance in last night's head to head debate today saying it was lucky he didn't cry and accusing him of having a tantrum.

"The fact he didn't burst out crying on the set probably counted for him," she said during a Radio Live question and answer session this morning.

Later in the day she didn't resile from her criticism telling reporters that expectations around Mr Key's performance before the debate were low and; "the fact he didn't collapse with a stress attack on the set probably gave him marks".

The two party leaders performed well in the debate, watched by 1.1 million New Zealanders, but because Mr Key was less experienced but did a good enough job to turn around a flat few days for National he was deemed by some to be the winner.

TVNZ's phone poll declared him ahead by a long way.

Miss Clark said the poll was worthless as it was self-selecting and there was a charge.

"That hasn't been the feedback we received. You've got to remember to call in on an 0900 number it costs money."

The text and phone poll cost 99 cents a vote - there were 47,000 votes.

Both leaders talked over and interrupted each other - something former National leader Don Brash wouldn't do because it was impolite to treat a woman that way.

At one point Miss Clark made a comment that Mr Key may shout at home but he wouldn't shout her down.

Today she said she was not accusing him of yelling at his family.

"What I meant was he was having a tantrum he was completely out of control trying to shout me down..."

Another reason he couldn't out shout her was that he didn't have a "voice advantage".

"I'm really referring to the fact that by women's voices I have a lower register by men's voices he has a higher one."

Miss Clark said there probably could have been more moderation.

"If the moderator isn't active then that will lead to the participants having to intervene themselves and that can lead to a lot of talking over.

"At the end of the day you can't let someone go on and on and on particularly if they're telling untruths."

Miss Clark said the way questions were asked by members of the public through You Tube was fresh but would have liked more from the experienced panel of journalists.

"I think the advantage of the seasoned political journalist is you can ask a question which is based on a lot of observation of the process and then you can drive on through. With the You Tube questions there was no follow up."

Last night Miss Clark said she did not think the campaign was bitter and today said she was just offering a professional analysis of how it went.

A spokesman for Mr Key said he would leave it to the public to decide.

"New Zealanders will judge the result of the debate."

Last night asked about his inexperience Mr Key said he just did his best.

"But I gave it my best shot and they (the public) will have a good sense of where a National government would take New Zealand."

- NZPA