The only way Campbell Live can be saved is by people watching the show, says the director of ratings website Throng.
Thousands of disgruntled fans have voiced their frustrations at yesterday's news that the prime-time current affairs show is under review and a petition to save the show has been launched.
Throng founder Regan Cunliffe said it was a logical commercial decision given the "massive" decline in audience which wasn't sustainable for TV3.
In 2013, the show was averaging an audience of 382,000. But in the same period this year it was drawing 191,000, Mr Cunliffe said.
"This isn't something that's just happened, this is a long-term trend over the last year and a half."
An uproar on social media and an online petition to save the show was useless unless people tuned in, Mr Cunliffe said.
"There's only one way to save Campbell Live, and only one petition you need to be involved in, and that's watching it.
"This is a commercial decision... the reality is unless MediaWorks can sell advertising around it, it's pointless."
Mr Cunliffe said he thought Campbell was a "great broadcaster" and the show wasn't doing anything wrong, but people's viewing habits had changed.He said most people arrive home from work at 7pm and wanted to be entertained, rather than watch current affairs.
"It's not that it's bad, I just think people get tired of it."
MediaWorks head of news Mark Jennings said in a statement a review was being carried out to improve commercial performance of the 7pm timeslot in a changing television market and was not a reflection of the quality of Campbell Live.
"Viewer expectations in 2015 are quite different from those of 2005 - and we need to constantly review our programming to ensure we are meeting those expectations," he said.It is understood a new soap is considered a front-runner to replace Campbell Live.