Prime Minister John Key says Campbell Live's primary role was to entertain rather than hold the Government to account.
He said viewers were more interested in "light entertainment" such as Campbell Live's rival Seven Sharp at that time of day.
Mr Key was asked on Newstalk ZB this morning whether it was bad for democracy if there were fewer commercial television shows holding the Government to account. He replied: "Its role in life isn't the hold the Government to account, it is to entertain its viewers and follow news stories. A great many of those don't involve the Government, some do."
Campbell Live is under review by TV3's MediaWorks owner as it revisits the 7pm time slot to try to improve ratings.
Mr Key said he had no inside knowledge about the review and any decision on its future was solely MediaWorks. Media reports indicated its possible demise was driven by commercial reality and low ratings.
"We live in a world where it is largely about commercial returns from what is a private radio station ... It's got a bunch of shareholders it needs to make a return to."
Mr Key said hour-long news bulletins were "struggling" even without tagging on an extra half hour current affairs show. "I'm not convinced it holds the audience. What you see is people zoning out."
Half-hour bulletins were now standard in the United States and he believed that was because online news sites and social media meant most people were already abreast of the news before 6pm.
"That's the challenge those programmes are up against. That's why [TVNZ] went away from Holmes and Close Up to Seven Sharp. It's more more breezy, magaziney show because people want light entertainment."
Mr Key also took a swipe at Labour's Clare Curran for her defence of Campbell Live, calling her "that girl."
He said he fronted on the show when asked unless his schedule did not allow it or another minister was better qualified to speak.
"I always front up. It was a laugh when I saw Clare Curran putting out some statement from Labour saying how great Campbell Live was. Gees, she must have no institutional knowledge, that girl, because it was Helen Clark who called John Campbell a 'little creep.'"
That was after Mr Campbell took Clark by surprise in an interview about the Corngate scandal in 2002. Mr Key said Clark refused to go on the show after that point. He said he would continue to go on it. "Whatever his sort of views are, I'm there defending our corner and so as long as the show is operational I'll do that."
He believed there was enough investment in public broadcasting.
Media commentator Gavin Ellis believes broadcasters have a moral obligation to hold those in power to account, through current affairs programming.
"If they won't voluntarily meet civic responsibility then maybe we need to look at some form of regulation to require them to provide good, competent, professional news and current affairs."
Ellis understands demand for entertainment content is on the rise in this fast-moving internet age.
"There is an equal appetite, I would say, for serious current affairs straight after the news. I really do lament the possibility of us losing that."
Gavin Ellis describes the current set-up of two main commercial networks, with no current affairs obligations, as 'laissez-faire' and questions the ability of broadcasters to produce quality current affairs without any form of regulation.
Online petitions calling to save Campbell Live have so far gathered tens of thousands of signatures.
A daily soap among the possible replacements if it goes.
Along with petitions, a Facebook group has been created urging TV3 bosses to keep Campbell Live and people are also writing to them directly.