Lyle Shelton has claimed same-sex marriage advocates who argued against a public vote “because someone might take their life” were guilty of “emotional blackmail”, saying the postal survey had proved the debate could be “fair and respectful”.

And in a warning shot to the Turnbull government as the campaign nears its end, Mr Shelton added that anyone “who thinks that these fights are over if the ‘Yes’ side wins are kidding themselves”.

“The government has bought themselves a lot more pain,” he said in an interview with The New Daily.

It comes as a Newspoll on Wednesday showed 59 per cent of those who have mailed their ballots have voted ‘Yes’, compared with 38 per cent for ‘No’, and after the ABS confirmed 67.5 per cent of Australians had already voted.

Mr Shelton, who is managing director of the Australian Christian Lobby, argued the postal survey showed “we can conduct this debate in a way that’s fair, respectful, that ventilates the necessary issues”.

‘Yes’ campaigners have so far focused on positive themes of love and equality. Photo: AAP

Asked about Nationals Senator Matt Canavan’s suggestion that people worried about the same-sex marriage debate should “grow a spine”, Mr Shelton replied: “Well, what’s wrong with that?”

He declined to concede the campaign had been a “difficult time for LGBTI Australians”.

“I think public debate should be allowed to happen,” he said.

“No one on our side wants harm to come to anyone, but the idea that we shouldn’t be allowed to speak or that we shouldn’t be allowed to have a plebiscite because someone might take their life, I think that’s emotional blackmail in the extreme.”

Last month, five mental health groups said same-sex marriage could prevent 3000 high school suicide attempts every year, Fairfax Media reported.

A 2013 Beyond Blue report quoted data saying same-sex attracted Australians had 14 times higher rates of suicide attempts than their heterosexual peers.

Equality Campaign spokeswoman Shirleene Robinson said: “It is not emotional blackmail to draw attention to the real harm that can come from abuse and negativity.”

‘Yes’ or ‘No’, fight to continue

The government has said it hopes same-sex marriage could be legislated before Christmas in the case of a ‘Yes’ vote.

Though he was “not conceding defeat”, Mr Shelton warned a ‘Yes’ vote would not put an end to the political fight, saying “politicians who thought we could have a plebiscite and get this off the agenda” were “naive”. Mr Shelton supported a public vote.

He claimed that if the ‘Yes’ side won, its supporters would “roll out Safe Schools everywhere” and that the ACL would “continue to oppose that”.

“What has happened in this campaign period is that we’ve awaked millions of Australians who are now alive to the political agenda of the ‘rainbow’ political movement,” he said.

Labor has paved the way for a fight over religious freedoms by confirming it would support WA Liberal senator Dean Smith’s bill in the case of a ‘Yes’ vote and oppose any amendments.

‘No’ advocates such as former PM John Howard have said more religious protections were needed.

Mr Shelton said he wanted legislative provisions that provided “for no detriment to Australians’ freedom of speech and religion”.

Matt Canavan said people worried about the same-sex marriage debate should “grow a spine”. Photo: AAP

The ‘No’ campaign vehicle, the Coalition For Marriage, has focused on what it says are the consequences of a law change, such as new limits on freedom of speech, freedom of religion and changes to sex education in schools.

He also claimed “most of the media have been campaigners for change” and that people had been “conditioned” for more than a decade to believe “this just involved a loving couple and there are no consequences beyond that”.

“They [the media] have believed that this is all about love and equality, whatever that means,” he said.

Analysis has showed the ‘No’ campaign had received four times as much campaign coverage as of September 20, and that Mr Shelton had been mentioned as much as the three leading ‘Yes’ campaigners combined.