The Prime Minister has rubbished opposition claims broadcaster Mike Hosking is politically biased.

"Personally I think that view is nonsense, that there's bias," John Key said.

"In my experience it doesn't matter what the personal views are of the journalist - they'll ask the hard questions."

Newstalk ZB and TVNZ Seven Sharp presenter Mike Hosking.

The debate over Hosking's opinions was sparked by an opinion piece NZ First leader Winston Peters wrote for the NZ Herald.

READ MORE: Had enough of Hosking?

Peters said Hosking's "jowls are up the Prime Minister's cheeks" and that the "quality of public debate suffers" because Hosking plays the role of "National Party stooge".

BENN BATHGATE/FAIRFAX NZ NZ First leader Winston Peters has hit out at presenter Mike Hosking for being out of touch with reality.

Labour leader Andrew Little and Green Party co-leader James Shaw backed Peters.

Little said Hosking made "no attempt at objectivity," while Shaw said it was "pretty obvious" Hosking was biased and there weren't any balancing voices with the same reach.

Hosking said on Seven Sharp on Monday night that he would address what he called a "small kerfuffle" on his Newstalk ZB radio show on Tuesday morning.

"I've just got a call from Winston Peters," he joked.

"There's nothing going on there," he said when his Seven Sharp co-host asked him what was going on.

"I'm going to address it on radio tomorrow morning," he said. "Small kerfuffle in the political circles."

Economic Development Minister Steven Joyce also entered the argument over Hosking's objectivity on Twitter.

Joyce said: "Opposition politicians outraged that a commentator is allowed to have a different view to them".

Joyce responded to critics on Twitter by suggesting they wanted "no opinions of any kind on govt-owned media outlets".

Hosking delivers his opinions twice daily via his Newstalk ZB morning show - which also appear on the NZ Herald website - and on TVNZ's Seven Sharp.

His comments are not confined to politics, although he often tackles political and economic stories, giving his view on issues and events.

During the 2014 election campaign, Labour initially objected to having Hosking as the moderator of a leaders' debate.

Key said Labour complained about Hosking leading up to the debate and then when he asked hard questions of Key the opposition "claimed victory" and said he was a great interviewer.

"The sooner the opposition parties realise that actually it's not the media they're at war with but it's convincing the New Zealand public of the merits in their arguments, the better," he said.

On his Kiwiblog website, National Party pollster David Farrar said at the time it was "pretty obvious[ly] that Mike Hosking has a centre-right worldview - just as John Campbell has a centre-left worldview".

OPPOSITION CLAIMS

Little said Hosking's dominance across so many media platforms was concerning.

"The point is that Mike Hosking is extremely influential because of his involvement with Newstalk ZB, TVNZ and the Herald."

Little accused Hosking of being "totally aligned to the Government of the day" and showing "no attempt at objectivity".

At fault was "broadcast media having opinionated people holding prime slots," he said.

Little said politicians had to work within the media landscape they were given and Parliament didn't "control the media and nor should we".

Shaw said the whole media industry was going through a period of "huge turmoil" and the result was a move away from reporting towards editorialising.

"Mike is symptomatic of a broader trend."

"The question is whether Mike thinks of himself more as an opinion leader than a journalist," Shaw said.

PETERS' ATTACK

In his piece, Peters was critical of an item Hosking delivered on the dairy industry - something Peters said Hosking knew nothing about.

Peters said farmers were well aware the "dairy industry is going through the floor" and Hosking had no idea of the grim reality.

"Mr Hosking has the temerity to believe that he knows more about what's happening down on the farm than the elected Member of Parliament of a dairy farming electorate, who comes off a dairy farm and knows the difference between a cow and a bull?"

"What is Mr Hosking's farming experience, his local organic supermarket?"

Peters says the facts are that dairy farmers had been told at the beginning of last season to budget on a $7/kg milksolids payout but Fonterra had since dwindled that down to $4.40.

"At the beginning of this season on May 28, Fonterra told its farmers to budget on $5.25, but a few weeks ago that was revised down to $3.85."

The payout could drop as low as $3.50, according to Peters, at which point provincial retailers from Kaitaia to Invercargill would see the spillover effects.

Peters wrote that Hosking and National were being seen as "fair weather friends" and Hosking's comments were drawing rebuke from farmers.

"One sharemilker wrote to (Hosking) saying, the tone was patronising. Live a day in our shoes first. I invite Mike to work for a full day before he says it's not a crisis."

Peters says Hosking wouldn't - "he'll send a Seven Sharp reporter instead".

Other criticisms Peters levelled of alleged bias involved Hosking's coverage of the 2014 general election and his response to Key's decision to send troops to Iraq.

Hosking was recorded as saying Key's decision to send troops was "brave and honourable".

Stuff contacted TVNZ seeking comment from Hosking, which was refused.